package Chart::Gnuplot;
use strict;
use vars qw($VERSION);
use Carp;
use File::Copy qw(move);
use File::Temp qw(tempdir);
use Chart::Gnuplot::Util qw(_lineType _pointType _borderCode _fillStyle _copy);
$VERSION = '0.23';

# Constructor
sub new
{
    my ($class, %hash) = @_;

    # Create temporary file to store Gnuplot instructions
    if (!defined $hash{_multiplot})     # if not in multiplot mode
    {
        my $dirTmp = tempdir(CLEANUP => 1);
        ($^O =~ /MSWin/)? ($dirTmp .= '\\'): ($dirTmp .= '/');
        $hash{_script} = $dirTmp . "plot";
    }

    # Default terminal: postscript terminal with color drawing elements
    if (!defined $hash{terminal} && !defined $hash{term})
    {
        $hash{terminal} = "postscript enhanced color";
        $hash{_terminal} = 'auto';
    }

    # Default setting
    if (defined $hash{output})
    {
        my @a = split(/\./, $hash{output});
        my $ext = $a[-1];
        $hash{terminal} .= " eps" if ($hash{terminal} =~ /^post/ &&
            $ext eq 'eps');
    }

    my $self = \%hash;
    return bless($self, $class);
}


# Generic attribute methods
sub AUTOLOAD
{
    my ($self, $key) = @_;
    my $attr = our $AUTOLOAD;
    $attr =~ s/.*:://;
    return if ($attr eq 'DESTROY');        # ignore destructor
    $self->{$attr} = $key if (defined $key);
    return($self->{$attr});
}


# General set method
sub set
{
    my ($self, %opts) = @_;
    foreach my $opt (keys %opts)
    {
        ($opts{$opt} eq 'on')? $self->$opt('') : $self->$opt($opts{$opt});
    }
    return($self);
}


# Add a 2D data set to the chart object
# - used with multiplot
sub add2d
{
    my ($self, @dataSet) = @_;
    push(@{$self->{_dataSets2D}}, @dataSet);
}


# Add a 3D data set to the chart object
# - used with multiplot
sub add3d
{
    my ($self, @dataSet) = @_;
    push(@{$self->{_dataSets3D}}, @dataSet);
}


# Add a 2D data set to the chart object
# - redirect to &add2d
# - for backward compatibility
sub add {&add2d(@_);}


# Plot 2D graphs
# - call _setChart()
#
# TODO:
# - Consider using pipe instead of system call
# - support MS time format: %{yyyy}-%{mmm}-%{dd} %{HH}:%{MM}
sub plot2d
{
    my ($self, @dataSet) = @_;
    &_setChart($self, \@dataSet);

    my $plotString = join(', ', map {$_->_thaw($self)} @dataSet);
    open(GPH, ">>$self->{_script}") || confess("Can't write $self->{_script}");
    print GPH "\nplot $plotString\n";
    close(GPH);

    # Generate image file
    &execute($self);
    return($self);
}


# Plot 3D graphs
# - call _setChart()
#
# TODO:
# - Consider using pipe instead of system call
# - support MS time format: %{yyyy}-%{mmm}-%{dd} %{HH}:%{MM}
sub plot3d
{
    my ($self, @dataSet) = @_;
    &_setChart($self, \@dataSet);

    my $plotString = join(', ', map {$_->_thaw($self)} @dataSet);
    open(GPH, ">>$self->{_script}") || confess("Can't write $self->{_script}");
    print GPH "\nsplot $plotString\n";
    close(GPH);

    # Generate image file
    &execute($self);
    return($self);
}


# Plot multiple plots in one single chart
sub multiplot
{
    my ($self, @charts) = @_;
    &_setChart($self);
    &_reset($self);

    open(PLT, ">>$self->{_script}") || confess("Can't write $self->{_script}");

    # Emulate the title when there is background color fill
    if (defined $self->{title} && defined $self->{bg})
    {
        print PLT "set label \"$self->{title}\" at screen 0.5, screen 1 ".
            "center offset 0,-1\n";
    }

    if (scalar(@charts) == 1 && ref($charts[0]) eq 'ARRAY')
    {
        my $nrows = scalar(@{$charts[0]});
        my $ncols = scalar(@{$charts[0][0]});
        &_setMultiplot($self, $nrows, $ncols);
    
        for (my $r = 0; $r < $nrows; $r++)
        {
            for (my $c = 0; $c < $ncols; $c++)
            {
                my $chart = $charts[0][$r][$c];
                $chart->_script($self->{_script});
                $chart->_multiplot(1);
                delete $chart->{bg};

                my $plot;
                my @dataSet;
                if (defined $chart->{_dataSets2D})
                {
                    $plot = 'plot';
                    @dataSet = @{$chart->{_dataSets2D}};
                }
                elsif (defined $chart->{_dataSets3D})
                {
                    $plot = 'splot';
                    @dataSet = @{$chart->{_dataSets3D}};
                }

                &_setChart($chart, \@dataSet);
                open(PLT, ">>$self->{_script}") ||
                    confess("Can't write $self->{_script}");
                print PLT "\n$plot ";
                print PLT join(', ', map {$_->_thaw($self)} @dataSet), "\n";
                close(PLT);
                &_reset($chart);
            }
        }
    }
    else
    {
        # Start multi-plot
        &_setMultiplot($self);

        foreach my $chart (@charts)
        {
            $chart->_script($self->{_script});
            $chart->_multiplot(1);
            delete $chart->{bg};

            my $plot;
            my @dataSet;
            if (defined $chart->{_dataSets2D})
            {
                $plot = 'plot';
                @dataSet = @{$chart->{_dataSets2D}};
            }
            elsif (defined $chart->{_dataSets3D})
            {
                $plot = 'splot';
                @dataSet = @{$chart->{_dataSets3D}};
            }
        
            &_setChart($chart, \@dataSet);
            open(PLT, ">>$self->{_script}") ||
                confess("Can't write $self->{_script}");
            print PLT "\n$plot ";
            print PLT join(', ', map {$_->_thaw($self)} @dataSet), "\n";
            close(PLT);
            &_reset($chart);
        }
    }
    close(PLT);

    # Generate image file
    &execute($self);
    return($self);
}


# Pass generic commands
sub command
{
    my ($self, $cmd) = @_;

    open(PLT, ">>$self->{_script}") || confess("Can't write $self->{_script}");
    (ref($cmd) eq 'ARRAY')?
        (print PLT join("\n", @$cmd), "\n"):
        (print PLT "$cmd\n");
    close(PLT);
    return($self);
}


# Set how the chart looks like
# - call _setTitle(), _setAxisLabel(), _setTics(), _setGrid(), _setBorder(),
#        _setTimestamp()
# - called by plot2d() and plot3d()
sub _setChart
{
    my ($self, $dataSets) = @_;
    my @sets = ();

    # Orientation
    $self->{terminal} .= " $self->{orient}" if (defined $self->{orient});

    # Set canvas size
    if (defined $self->{imagesize})
    {
        my ($ws, $hs) = split(/,\s?/, $self->{imagesize});
        if (defined $self->{_terminal} && $self->{_terminal} eq 'auto')
        {
            # for post terminal
            if (defined $self->{orient} && $self->{orient} eq 'portrait')
            {
                $ws *= 7 if ($ws =~ /^([1-9]\d*)?0?(\.\d+)?$/);
                $hs *= 10 if ($hs =~ /^([1-9]\d*)?0?(\.\d+)?$/);
            }
            else
            {
                $ws *= 10 if ($ws =~ /^([1-9]\d*)?0?(\.\d+)?$/);
                $hs *= 7 if ($hs =~ /^([1-9]\d*)?0?(\.\d+)?$/);
            }
        }
        $self->{terminal} .= " size $ws,$hs";
    }

    # Prevent changing terminal in multiplot mode
    delete $self->{terminal} if (defined $self->{_multiplot});

    # Start writing gnuplot script
    my $pltTmp = $self->{_script};
    open(PLT, ">>$pltTmp") || confess("Can't write gnuplot script $pltTmp");

    # Set character encoding
    #
    # Quote from Gnuplot manual:
    # "Generally you must set the encoding before setting the terminal type."
    if (defined $self->{encoding})
    {
        print PLT "set encoding $self->{encoding}\n";
    }

    # Chart background color
    if (defined $self->{bg})
    {
        my $bg = $self->{bg};
        if (ref($bg) eq 'HASH')
        {
            print PLT "set object rect from screen 0, screen 0 to ".
                "screen 1, screen 1 fillcolor rgb \"$$bg{color}\"";
            print PLT " fillstyle solid $$bg{density}" if
                (defined $$bg{density});
            print PLT " behind\n";
        }
        else
        {
            print PLT "set object rect from screen 0, screen 0 to ".
                "screen 1, screen 1 fillcolor rgb \"$bg\" behind\n";
        }
        push(@sets, 'object');
    }

    # Plot area background color
    if (defined $self->{plotbg})
    {
        my $bg = $self->{plotbg};
        if (ref($bg) eq 'HASH')
        {
            print PLT "set object rect from graph 0, graph 0 to ".
                "graph 1, graph 1 fillcolor rgb \"$$bg{color}\"";
            print PLT " fillstyle solid $$bg{density}" if
                (defined $$bg{density});
            print PLT " behind\n";
        }
        else
        {
            print PLT "set object rect from graph 0, graph 0 to ".
                "graph 1, graph 1 fillcolor rgb \"$bg\" behind\n";
        }
        push(@sets, 'object');
    }

    # Set date/time data
    #
    # For xrange to work for time-sequence, time-axis ("set xdata time")
    # and timeformat ("set timefmt '%Y-%m-%d'") MUST be set BEFORE 
    # the range command ("set xrange ['2009-01-01','2009-01-07']")
    #
    # Thanks to Holyspell
    if (defined $self->{timeaxis})
    {
        my @axis = split(/,\s?/, $self->{timeaxis});
        foreach my $axis (@axis)
        {
            print PLT "set $axis"."data time\n";
            push(@sets, $axis."data");
        }

        foreach my $ds (@$dataSets)
        {
            if (defined $ds->{timefmt})
            {
                print PLT "set timefmt \"$ds->{timefmt}\"\n";
                last;
            }
        }
    }

    # Parametric plot
    foreach my $ds (@$dataSets)
    {
        # Determine if there is paramatric plot
        if (defined $ds->{func} && ref($ds->{func}) eq 'HASH')
        {
            $self->{parametric} = '';
            last;
        }
    }

    my $setGrid = 0;    # detect whether _setGrid has been run

    # Loop and process other chart options
    foreach my $attr (keys %$self)
    {
        if ($attr eq 'output')
        {
            print PLT "set output \"$self->{output}\"\n";
        }
        elsif ($attr eq 'title')
        {
            print PLT "set title ".&_setTitle($self->{title})."\n";
            push(@sets, 'title')
        }
        elsif ($attr =~ /^((x|y)2?|z)label$/)
        {
            print PLT "set $attr ".&_setAxisLabel($self->{$attr})."\n";
            push(@sets, $attr);
        }
        elsif ($attr =~ /^((x|y)2?|z|t|u|v)range$/)
        {
            if (ref($self->{$attr}) eq 'ARRAY')
            {
                # Deal with ranges from array reference
                if (defined $self->{timeaxis} &&
                    $self->{timeaxis} =~ /(^|,)\s*$1\s*(,|$)/)
                {
                    # $1-axis is a time axis
                    print PLT "set $attr ['".join("':'", @{$self->{$attr}}).
                        "']\n";
                }
                else
                {
                    print PLT "set $attr [".join(":", @{$self->{$attr}})."]\n";
                }
            }
            elsif ($self->{$attr} eq 'reverse')
            {
                print PLT "set $attr [*:*] reverse\n";
            }
            else
            {
                print PLT "set $attr $self->{$attr}\n";
            }
            push(@sets, $attr);
        }
        elsif ($attr =~ /^(x|y|x2|y2|z)tics$/)
        {
            if (defined $self->{$attr})
            {
                my ($axis) = ($attr =~ /^(.+)tics$/);
                print PLT "set $attr".&_setTics($self->{$attr})."\n";
                if (ref($self->{$attr}) eq 'HASH')
                {
                    if (defined ${$self->{$attr}}{labelfmt})
                    {
                        print PLT "set format $axis ".
                            "\"${$self->{$attr}}{labelfmt}\"\n";
                        push(@sets, 'format');
                    }
                    if (defined ${$self->{$attr}}{minor})
                    {
                        my $nTics = ${$self->{$attr}}{minor}+1;
                        print PLT "set m$axis"."tics $nTics\n";
                        push(@sets, "m$axis"."tics");
                    }
                }
                push(@sets, $attr);
            }
            else
            {
                print PLT "unset $attr\n";
            }
        }
        elsif ($attr eq 'legend')
        {
            print PLT "set key".&_setLegend($self->{legend})."\n";
            push(@sets, 'key');
        }
        elsif ($attr eq 'border')
        {
            if (defined $self->{border})
            {
                print PLT "set border";
                print PLT " ".&_borderCode($self->{border}->{sides}) if
                    (defined $self->{border}->{sides});
                print PLT &_setBorder($self->{border})."\n";
                push(@sets, 'border');
            }
            else
            {
                print PLT "unset border\n";
            }
        }
        elsif ($attr =~ /^(minor)?grid$/)
        {
            next if ($setGrid == 1);

            print PLT "set grid".&_setGrid($self)."\n";
            push(@sets, 'grid');
            $setGrid = 1;
        }
        elsif ($attr eq 'timestamp')
        {
            print PLT "set timestamp".&_setTimestamp($self->{timestamp})."\n";
            push(@sets, 'timestamp');
        }
        elsif ($attr eq 'terminal')
        {
            print PLT "set $attr $self->{$attr}\n";
        }
        # Non-gnuplot options / options specially treated before
        elsif (!grep(/^$attr$/, qw(
                gnuplot
                convert
                encoding
                imagesize
                orient
                bg
                plotbg
                timeaxis
            )) &&
            $attr !~ /^_/)
        {
            (defined $self->{$attr} && $self->{$attr} ne '')?
                (print PLT "set $attr $self->{$attr}\n"):
                (print PLT "set $attr\n");
            push(@sets, $attr);
        }
    }

    # Write labels
	my $isLabelSet = 0;
    foreach my $label (@{$self->{_labels}})
    {
        print PLT "set label"."$label\n";
		push(@sets, "label") if ($isLabelSet == 0);
		$isLabelSet = 1;
    }

    # Draw arrows
	my $isArrowSet = 0;
    foreach my $arrow (@{$self->{_arrows}})
    {
        print PLT "set arrow"."$arrow\n";
		push(@sets, "arrow") if ($isArrowSet == 0);
		$isArrowSet = 1;
    }

    # Draw objects
	my $isObjectSet = 0;
    foreach my $object (@{$self->{_objects}})
    {
        print PLT "set object"."$object\n";
		push(@sets, "object") if ($isObjectSet == 0);
		$isObjectSet = 1;
    }
    close(PLT);

    $self->_sets(\@sets);
}


# Set the details of the title
# - called by _setChart()
#
# Usage example:
# title => {
#     text   => "My title",
#     font   => "arial, 14",
#     color  => "brown",
#     offset => "0, -1",
# },
sub _setTitle
{
    my ($title) = @_;
    if (ref($title))
    {
        my $out = "\"$$title{text}\"";
        $out .= " offset $$title{offset}" if (defined $$title{offset});

        # Font and size
        my $font;
        $font = $$title{font} if (defined $$title{font});
        $font .= ",$$title{fontsize}" if (defined $$title{fontsize});
        $out .= " font \"$font\"" if (defined $font);

        # Color
        $out .= " textcolor rgb \"$$title{color}\"" if (defined $$title{color});

        # Switch of the enhanced mode. Default: off
        $out .= " noenhanced" if (!defined $$title{enhanced} ||
            $$title{enhanced} ne 'on');
        return($out);
    }
    else
    {
        return("\"$title\" noenhanced");
    }
}


# Set the details of the axis labels
# - called by _setChart()
#
# Usage example:
# xlabel => {
#     text   => "My x-axis label",
#     font   => "arial, 14",
#     color  => "brown",
#     offset => "0, -1",
#     rotate => 45,
# },
#
# TODO
# - support radian and pi in "rotate"
sub _setAxisLabel
{
    my ($label) = @_;
    if (ref($label))
    {
        my $out = "\"$$label{text}\"";

        # Location offset
        $out .= " offset $$label{offset}" if (defined $$label{offset});

        # Font and size
        my $font;
        $font = $$label{font} if (defined $$label{font});
        $font .= ",$$label{fontsize}" if (defined $$label{fontsize});
        $out .= " font \"$font\"" if (defined $font);

        # Color
        $out .= " textcolor rgb \"$$label{color}\"" if (defined $$label{color});

        # Switch of the enhanced mode. Default: off
        $out .= " noenhanced" if (!defined $$label{enhanced} ||
            $$label{enhanced} ne 'on');

        # Text rotation
        $out .= " rotate by $$label{rotate}" if (defined $$label{rotate});
        return($out);
    }
    else
    {
        return("\"$label\" noenhanced");
    }
}


# Set the details of the tics and tic labels
# - called by _setChart()
#
# Usage example:
# xtics => {
#    along     => 'border',
#    labels    => [-10, 15, 20, 25],
#    labelfmt  => "%3f",
#    font      => "arial",
#    fontsize  => 14,
#    fontcolor => "brown",
#    offset    => "0, -1",
#    start     => -10,
#    incr      => 0.2,
#    end       => 2.6,
#    rotate    => 45,
#    length    => "2,1",
#    along     => 'axis',
#    minor     => 3,
#    mirror    => 'off',
# },
#
# TODO
# - implement "add" option to add addition tics other than default
# - support radian and pi in "rotate"
sub _setTics
{
    my ($tic) = @_;

    my $out = '';
    if (ref($tic) eq 'HASH')
    {
        $out .= " $$tic{along}" if (defined $$tic{along});
        $out .= " nomirror" if (
            defined $$tic{mirror} && $$tic{mirror} eq 'off'
        );
        $out .= " scale $$tic{length}" if (defined $$tic{length});
        $out .= " rotate by $$tic{rotate}" if (defined $$tic{rotate});
        $out .= " offset $$tic{offset}" if (defined $$tic{offset});
		
		# Tic labels
		if (defined $$tic{incr})
		{
			my $location = $$tic{incr};
			if (defined $$tic{start})
			{
				$location = "$$tic{start},$location";
				$location .= ",$$tic{end}" if (defined $$tic{end});
			}

			$location = '0'.$location if ($location =~ /^\-/);
			$out .= " $location";
		}
        $out .= " (". join(',', @{$$tic{labels}}) . ")" if
            (defined $$tic{labels});

        # Font, font size and font color
        if (defined $$tic{font})
        {
            my $font = $$tic{font};
            $font = "$$tic{font},$$tic{fontsize}" if ($font !~ /\,/ &&
                defined $$tic{fontsize});
            $out .= " font \"$font\"";
        }
        $out .= " textcolor rgb \"$$tic{fontcolor}\"" if
            (defined $$tic{fontcolor});
    }
    elsif (ref($tic) eq 'ARRAY')
    {
        $out = " (". join(',', @$tic) . ")";
    }
    elsif ($tic ne 'on')
    {
        $out = "\"$tic\"";
    }
    return($out);
}


# Set the details of the grid lines
# - called by _setChart()
#
# Usage example:
# grid => {
#     type    => 'dash, dot',    # default: dot
#     width   => 2,              # default: 0
#     color   => 'blue',         # default: black
#     xlines  => 'on',           # default: on
#     ylines  => 'off',          # default: on
#     zlines  => 'off',          # default:
#     x2lines => 'off',          # default: off
#     y2lines => 'off',          # default: off
#     layer   => 'front',        # default: layerdefault
# },
#
# minorgrid => {
#     width   => 1,              # default: 0
#     color   => 'gray',         # default: black
#     xlines  => 'on',           # default: off
#     ylines  => 'on',           # default: off
#     x2lines => 'off',          # default: off
#     y2lines => 'off',          # default: off
#     layer   => 'front',        # default: layerdefault
# }
#
# # OR
# 
# grid => 'on',
#
# TODO:
# - support polar grid
sub _setGrid
{
    my ($self) = @_;
    my $grid = $self->{grid};
    my $mgrid = $self->{minorgrid} if (defined $self->{minorgrid});

    my $out = '';
    if (ref($grid) eq 'HASH' || ref($mgrid) eq 'HASH')
    {
        $grid = &_gridString2Hash($grid);
        $mgrid = &_gridString2Hash($mgrid);

        # Set whether the major grid lines are drawn
        (defined $$grid{xlines} && $$grid{xlines} =~ /^off/)?
            ($out .= " noxtics"): ($out .= " xtics");
        (defined $$grid{ylines} && $$grid{ylines} =~ /^off/)?
            ($out .= " noytics"): ($out .= " ytics");
        (defined $$grid{zlines} && $$grid{zlines} =~ /^off/)?
            ($out .= " noztics"): ($out .= " ztics");

        # Set whether the vertical minor grid lines are drawn
        $out .= " mxtics" if ( (defined $$grid{xlines} &&
            $$grid{xlines} =~ /,\s?on$/) ||
            (defined $self->{minorgrid} && (!defined $$mgrid{xlines} ||
            $$mgrid{xlines} eq 'on')) );

        # Set whether the horizontal minor grid lines are drawn
        $out .= " mytics" if ( (defined $$grid{ylines} &&
            $$grid{ylines} =~ /,\s?on$/) ||
            (defined $mgrid && (!defined $$mgrid{ylines} ||
            $$mgrid{ylines} eq 'on')) );

        # Major grid on secondary axes
        $out .= " x2tics" if (defined $$grid{x2lines} &&
            $$grid{x2lines} eq 'on');
        $out .= " y2tics" if (defined $$grid{y2lines} &&
            $$grid{y2lines} eq 'on');

        # Minor grid on secondary axes
        $out .= " mx2tics" if (defined $$mgrid{x2lines} &&
            $$mgrid{x2lines} eq 'on');
        $out .= " my2tics" if (defined $$mgrid{y2lines} &&
            $$mgrid{y2lines} eq 'on');

		# Set the layer
		$out .= " $$grid{layer}" if (defined $$grid{layer});

        # Set the line type of the grid lines
        my $major = my $minor = '';
        my $majorType = my $minorType = 4;  # dotted lines
        if (defined $$grid{linetype})
        {
            $majorType = $minorType = $$grid{linetype};
            ($majorType, $minorType) = split(/\,\s?/, $$grid{linetype}) if
                ($$grid{linetype} =~ /\,/);
        }
        $minorType = $$mgrid{linetype} if (defined $$mgrid{linetype});
        $major .= " linetype ".&_lineType($majorType);
        $minor .= " linetype ".&_lineType($minorType);
        
        # Set the line width of the grid lines
        my $majorWidth = my $minorWidth = 0;
        if (defined $$grid{width})
        {
            $majorWidth = $minorWidth = $$grid{width};
            ($majorWidth, $minorWidth) = split(/\,\s?/, $$grid{width}) if
                ($$grid{width} =~ /\,/);
        }
        $minorWidth = $$mgrid{width} if (defined $$mgrid{width});
        $major .= " linewidth $majorWidth";
        $minor .= " linewidth $minorWidth";

        # Set the line color of the grid lines
        my $majorColor = my $minorColor = 'black';
        if (defined $$grid{color})
        {
            $majorColor = $minorColor = $$grid{color};
            ($majorColor, $minorColor) = split(/\,\s?/, $$grid{color}) if
                ($$grid{color} =~ /\,/);
        }
        $minorColor = $$mgrid{color} if (defined $$mgrid{color});
        $major .= " linecolor rgb \"$majorColor\"";
        $minor .= " linecolor rgb \"$minorColor\"";
        $out .= "$major" if ($major ne '');
        $out .= ",$minor" if ($minor ne '');
    }
    else
    {
        if (defined $grid)
        {
            return(" $grid") if ($grid !~ /^(on|off)$/);
            ($grid eq 'off')? ($out = " noxtics noytics"):
                ($out = " xtics ytics");
        }
        $out .= " mxtics mytics" if (defined $mgrid && $mgrid eq 'on');
    }
    return($out);
}


# Convert grid string to hash
# - called by _setGrid
sub _gridString2Hash
{
    my ($grid) = @_;
    return($grid) if (ref($grid) eq 'HASH');

    my %out;
    $out{xlines} = $out{ylines} = $out{zlines} = $grid;
    return(\%out);
}


# Set the details of the graph border and legend box border
# - called by _setChart()
#
# Usage example:
# border => {
#      linetype => 3,            # default: solid
#      width    => 2,            # default: 0
#      color    => '#ff00ff',    # default: system defined
#      layer    => 'back',       # default: front
# },
#
# Remark:
# - By default, the color of the axis tics would follow the border unless
#   specified otherwise.
sub _setBorder
{
    my ($border) = @_;

    my $out = '';
	$out .= " $$border{layer}" if (defined $$border{layer});
    $out .= " linetype ".&_lineType($$border{linetype}) if
        (defined $$border{linetype});
    $out .= " linecolor rgb \"$$border{color}\"" if (defined $$border{color});
    $out .= " linewidth $$border{width}" if (defined $$border{width});
    return($out);
}


# Format the legend (key)
#
# Usage example:
# legend => {
#    position => "outside bottom",
#    width    => 3,
#    height   => 4,
#    align    => "right",
#    order    => "horizontal reverse",
#    title    => "Title of the legend",
#    sample   => {
#        length   => 3,
#        position => "left",
#        spacing  => 2,
#    },
#    border   => {
#        linetype => 2,
#        width    => 1,
#        color    => "blue",
#    },
# },
sub _setLegend
{
    my ($legend) = @_;

    my $out = '';
    if (defined $$legend{position})
    {
        ($$legend{position} =~ /\d/)? ($out .= " at $$legend{position}"):
            ($out .= " $$legend{position}");
    }
    $out .= " width $$legend{width}" if (defined $$legend{width});
    $out .= " height $$legend{height}" if (defined $$legend{height});
    if (defined $$legend{align})
    {
        $out .= " Left" if ($$legend{align} eq 'left');
        $out .= " Right" if ($$legend{align} eq 'right');
    }
    if (defined $$legend{order})
    {
        my $order = $$legend{order};
        $order =~ s/reverse/invert/;
        $out .= " $order";
    }
    if (defined $$legend{title})
    {
        if (ref($$legend{title}) eq 'HASH')
        {
            my $title = $$legend{title};
            $out .= " title \"$$title{text}\"";
            $out .= " noenhanced" if (!defined $$title{enhanced} ||
                $$title{enhanced} ne 'on');
        }
        else
        {
            $out .= " title \"$$legend{title}\" noenhanced";
        }
    }
    if (defined $$legend{sample})
    {
        $out .= " samplen $$legend{sample}{length}" if
            (defined $$legend{sample}{length});
        $out .= " reverse" if (defined $$legend{sample}{position} ||
            $$legend{sample}{position} eq "left");
        $out .= " spacing $$legend{sample}{spacing}" if
            (defined $$legend{sample}{spacing});
    }
    if (defined $$legend{border})
    {
        if (ref($$legend{border}) eq 'HASH')
        {
            $out .= " box ".&_setBorder($$legend{border});
        }
        elsif ($$legend{border} eq "off")
        {
            $out .= " no box";
        }
        elsif ($$legend{border} eq "on")
        {
            $out .= " box";
        }
    }
    return($out);
}


# Set title and layout of the multiplot
sub _setMultiplot
{
    my ($self, $nrows, $ncols) = @_;

    open(PLT, ">>$self->{_script}") || confess("Can't write $self->{_script}");
    print PLT "set multiplot";
    print PLT " title \"$self->{title}\"" if (defined $self->{title});
    print PLT " layout $nrows, $ncols" if (defined $nrows);
    print PLT "\n";
    close(PLT);
}


# Usage example:
# timestamp => {
#    fmt    => '%d/%m/%y %H:%M',
#    offset => "10,-3"
#    font   => "Helvetica",
# },
# # OR
# timestamp => 'on';
sub _setTimestamp
{
    my ($ts) = @_;

    my $out = '';
    if (ref($ts) eq 'HASH')
    {
        $out .= " \"$$ts{fmt}\"" if (defined $$ts{fmt});
        $out .= " offset $$ts{offset}" if (defined $$ts{offset});
        $out .= " font \"$$ts{font}\"" if (defined $$ts{font});
    }
    elsif ($ts ne 'on')
    {
        return($ts);
    }
    return($out);
}


# Call Gnuplot to generate the image file
sub execute
{
    my ($self) = @_;

    # Try to find the executable of Gnuplot
    my $gnuplot = 'gnuplot';
    if (defined $self->{gnuplot})
    {
        $gnuplot = $self->{gnuplot};
    }
    else
    {
        if ($^O =~ /MSWin/)
        {
            my $gnuplotDir = 'C:\Program Files\gnuplot';
            $gnuplotDir = 'C:\Program Files (x86)\gnuplot' if (!-e $gnuplotDir);

            my $binDir = $gnuplotDir.'\bin';
            $binDir = $gnuplotDir.'\binary' if (!-e $binDir);

            $gnuplot = $binDir.'\gnuplot.exe';
            if (!-e $gnuplot)
            {
                $gnuplot = $binDir.'\wgnuplot.exe';
                confess("Gnuplot command not found.") if (!-e $gnuplot);
            }
        }
    }

    # Execute gnuplot
    my $cmd = qq("$gnuplot" "$self->{_script}");
    $cmd .= " -" if ($self->{terminal} =~ /^(ggi|pm|windows|wxt|x11)(\s|$)/);
    my $err = `$cmd 2>&1`;
#    my $err;
#    system("$cmd");

    # Capture and process error message from Gnuplot
    if (defined $err && $err ne '')
    {
        my ($errTmp) = ($err =~ /\", line \d+:\s(.+)/);
        die "$errTmp\n" if (defined $errTmp);
        warn "$err\n";
    }

    # Convert the image to the user-specified format
    if (defined $self->{_terminal} && $self->{_terminal} eq 'auto')
    {
        my @a = split(/\./, $self->{output});
        my $ext = $a[-1];
        &convert($self, $ext) if ($ext !~ /^e?ps$/);
    }

    return($self);
}


# Unset the chart properties
# - called by multiplot()
sub _reset
{
    my ($self) = @_;
    open(PLT, ">>$self->{_script}") || confess("Can't write $self->{_script}");
    foreach my $opt (@{$self->{_sets}})
    {
        print PLT "unset $opt\n";

        if ($opt =~ /range$/)
        {
            print PLT "set $opt [*:*]\n";
        }
        elsif (!grep(/^$opt$/, qw(arrow grid label logscale object parametric))
			&& $opt !~ /tics$/)
        {
            print PLT "set $opt\n";
        }
    }
    close(PLT);
}


# Arbitrary labels placed in the chart
#
# Usage example:
# $chart->label(
#     text       => "This is a label",
#     position   => "0.2, 3 left",
#     offset     => "2,2",
#     rotate     => 45,
#     font       => "arial, 15",
#     fontcolor  => "dark-blue",
#     pointtype  => 3,
#     pointsize  => 5,
#     pointcolor => "blue",
#     layer      => "front",
# );
sub label
{
    my ($self, %label) = @_;

    my $out = " \"$label{text}\"";
    $out .= " at $label{position}" if (defined $label{position});
    $out .= " offset $label{offset}" if (defined $label{offset});
    $out .= " rotate by $label{rotate}" if (defined $label{rotate});
    $out .= " font \"$label{font}\"" if (defined $label{font});
	$out .= " $label{layer}" if (defined $label{layer});
    $out .= " textcolor rgb \"$label{fontcolor}\"" if
        (defined $label{fontcolor});
    $out .= " noenhanced" if (!defined $label{enhanced} ||
        $label{enhanced} ne 'on');

    if (defined $label{pointtype} || defined $label{pointsize} ||
        defined $label{pointcolor})
    {
        $out .= " point";
        $out .= " pointtype ".&_pointType($label{pointtype}) if
            (defined $label{pointtype});
        $out .= " pointsize $label{pointsize}" if (defined $label{pointsize});
        $out .= " linecolor rgb \"$label{pointcolor}\"" if
            (defined $label{pointcolor});
    }

    push(@{$self->{_labels}}, $out);
    return($self);
}


# Arbitrary arrows placed in the chart
#
# Usage example:
# $chart->arrow(
#     from     => "0,2",
#     to       => "0.3,0.1",
#     linetype => 'dash',
#     width    => 2,
#     color    => "dark-blue",
#     head     => {
#         size      => 3,
#         angle     => 30,
#         direction => 'back',
#     },
#     layer    => "front",
# );
sub arrow
{
    my ($self, %arrow) = @_;
    confess("Starting position of arrow not found") if (!defined $arrow{from});

    my $out = " from $arrow{from}";
    $out .= " to $arrow{to}" if (defined $arrow{to});
    $out .= " rto $arrow{rto}" if (defined $arrow{rto});
	$out .= " $arrow{layer}" if (defined $arrow{layer});
    $out .= " linetype ".&_lineType($arrow{linetype}) if
        (defined $arrow{linetype});
    $out .= " linewidth $arrow{width}" if (defined $arrow{width});
    $out .= " linecolor rgb \"$arrow{color}\"" if (defined $arrow{color});
    $out .= " size $arrow{headsize}" if (defined $arrow{headsize});

    # Set arrow head
    $out .= &_setArrowHead($arrow{head}) if (defined $arrow{head});

    push(@{$self->{_arrows}}, $out);
    return($self);
}


# Arbitrary lines placed in the chart
#
# Usage example:
# $chart->line(
#     from     => "0,2",
#     to       => "0.3,0.1",
#     linetype => 'dash',
#     width    => 2,
#     color    => "dark-blue",
#     layer    => "front",
# );
sub line
{
    my ($self, %line) = @_;
    confess("Starting position of line not found") if (!defined $line{from});

    my $out = " from $line{from}";
    $out .= " to $line{to}" if (defined $line{to});
    $out .= " rto $line{rto}" if (defined $line{rto});
	$out .= " $line{layer}" if (defined $line{layer});
    $out .= " linetype ".&_lineType($line{linetype}) if
        (defined $line{linetype});
    $out .= " linewidth $line{width}" if (defined $line{width});
    $out .= " linecolor rgb \"$line{color}\"" if (defined $line{color});

    push(@{$self->{_arrows}}, "$out nohead");    # remove arrow head
    return($self);
}


# Set the options of arrow head
sub _setArrowHead
{
    my ($head) = @_;
    my $out = '';

    # Author's comments:
    # - The filling of arrow head does not follow the convention of fill style
    #   of objects and plotting styles. Perhaps Gnuplot will change this in the
    #   future.
    # - Back-angle is not meaningful if filling is "nofilled". This constraint
    #   may be removed theoretically.
    # - Therefore, "backangle" and "fill" are disabled for the moment.
    if (ref($head) eq 'HASH')
    {
        my $size = (defined $$head{size})? $$head{size} : 0.45;
        my $angle = (defined $$head{angle})? $$head{angle} : 15;
        confess("arrow head size must be greater than 0") if ($size <= 0);

        $out .= " size $size";
        $out .= ",$angle" if ($size !~ /,/);
#        $out .= ",$$head{backangle}" if (defined $$head{backangle});
#        $out .= " $$head{fill}" if (defined $$head{fill});
        if (defined $$head{direction})
        {
            if ($$head{direction} eq 'back')
            {
                $out .= " backhead";
            }
            elsif ($$head{direction} eq 'both')
            {
                $out .= " heads";
            }
            elsif ($$head{direction} eq 'off')
            {
                $out .= " nohead";
            }
        }
    }
    else
    {
        if ($head eq 'off')
        {
            $out .= " nohead";
        }
        elsif ($head eq 'back')
        {
            $out .= " backhead";
        }
        elsif ($head eq 'both')
        {
            $out .= " heads";
        }
    }

    return($out);
}


# Arbitrary rectangles placed in the chart
#
# Usage example:
# $chart->rectangle(
#     from => "screen 0.2, screen 0.2",
#     to   => "screen 0.4, screen 0.4",
#     fill => {
#         density => 0.2,
#         color   => "#11ff11",
#     },
#     border => {color => "blue"},
# );
sub rectangle
{
    my ($self, %rect) = @_;

    # Position and dimension of the rectangle
    my $out = "";
    $out .= " $rect{index}" if (defined $rect{index});
    $out .= " rectangle";

    if (defined $rect{from})
    {
        $out .= " from $rect{from}";
        
        if (defined $rect{to})
        {
            $out .= " to $rect{to}";
        }
        elsif (defined $rect{rto})
        {
            $out .= " rto $rect{rto}";
        }
        else
        {
            confess("Rectangle dimension not complete");
        }
    }
    elsif (defined $rect{width})
    {
        $rect{at} = $rect{center} if (defined $rect{center});
        confess("Rectangle position not complete") if (!defined $rect{at});
        confess("Rectangle dimension not found") if (!defined $rect{width} ||
            !defined $rect{height});

        $out .= " at $rect{at} size $rect{width},$rect{height}";
    }
    else
    {
        confess("Rectangle position or dimension not complete");
    }

    # Process shared object options
    $out .= &_setObjOpt(\%rect);

    push(@{$self->{_objects}}, $out);
    return($self);
}


# Arbitrary ellipses placed in the chart
#
# Usage example:
# $chart->ellipse(
#     at     => "screen 0.2, screen 0.2",
#     width  => 0.2,
#     height => 0.5
#     fill   => {
#         density => 0.2,
#         color   => "#11ff11",
#     },
#     border => {color => "blue"},
# );
sub ellipse
{
    my ($self, %elli) = @_;

    # - Alias of "at": "center"
    # - Check position and dimension information
    $elli{at} = $elli{center} if (defined $elli{center});
    confess("Ellipse location not found") if (!defined $elli{at});
    confess("Ellipse dimension not found") if (!defined $elli{width} ||
        !defined $elli{height});

    my $out = "";
    $out .= " $elli{index}" if (defined $elli{index});
    $out .= " ellipse at $elli{at} size $elli{width},$elli{height}";
    $out .= " units $elli{units}" if (defined $elli{units});

    # Process shared object options
    $out .= &_setObjOpt(\%elli);

    push(@{$self->{_objects}}, $out);
    return($self);
}


# Arbitrary circles placed in the chart
#
# Usage example:
# $chart->circle(
#     at   => "screen 0.2, screen 0.2",
#     size => 0.5
#     fill => {
#         density => 0.2,
#         color   => "#11ff11",
#     },
#     border => {color => "blue"},
# );
sub circle
{
    my ($self, %cir) = @_;

    # - Alias of "at": "center"
    # - Check position and size information
    $cir{at} = $cir{center} if (defined $cir{center});
    confess("Circle location not found") if (!defined $cir{at});
    confess("Circle size not found") if (!defined $cir{size});

    my $out = "";
    $out .= " $cir{index}" if (defined $cir{index});
    $out .= " circle at $cir{at} size $cir{size}";

    if (defined $cir{arc})
    {
        (ref($cir{arc}) eq 'ARRAY')?
            ($out .= " arc [". join(':', @{$cir{arc}}) . "]"):
            ($out .= " arc [$cir{arc}]");
    }

    # Process shared object options
    $out .= &_setObjOpt(\%cir);

    push(@{$self->{_objects}}, $out);
    return($self);
}


# Arbitrary polygons placed in the chart
#
# Usage example:
# $chart->polygon(
#     vertices => [
#         "0, -0.6",
#         {rto => "-1, 0.3"},
#         {to => [-4, 0.4]},
#     ],
# );
sub polygon
{
    my ($self, %poly) = @_;
    confess("Polygon vertices not found") if (!defined $poly{vertices});

    my $v = $poly{vertices};
    confess("Polygon starting vertex not found") if (scalar(@$v) < 0.5);

    my $out = "";
    $out .= " $poly{index}" if (defined $poly{index});
    $out .= " polygon from $$v[0]";

    # Other vertices
    for (my $i = 1; $i < @$v; $i++)
    {
        if (ref($$v[$i]) eq 'HASH')
        {
            my @key = keys(%{$$v[$i]});
            my @val = values(%{$$v[$i]});
            $out .= " $key[0] $val[0]";
        }
        else
        {
            $out .= " to $$v[$i]";
        }
    }

    # Process shared object options
    $out .= &_setObjOpt(\%poly);

    push(@{$self->{_objects}}, $out);
    return($self);
}


# Set the details common to all objects
sub _setObjOpt
{
    my ($obj) = @_;
    my $out = "";
    $out .= " $$obj{layer}" if (defined $$obj{layer});
    $out .= " linewidth $$obj{linewidth}" if (defined $$obj{linewidth});

    # Set filling color / pattern and border
    if (defined $$obj{fill})
    {
        my $fill = $$obj{fill};
        $out .= " fillcolor rgb \"$$fill{color}\"" if (defined $$fill{color});
        $out .= " fillstyle". &_fillStyle($fill);

        # Set details of the border
        if (defined $$obj{border})
        {
            if (ref($$obj{border}) eq 'HASH')
            {
                $out .= " border";
                $out .= " linecolor rgb \"$$obj{border}{color}\"" if
                    (defined $$obj{border}{color});
            }
            elsif ($$obj{border} =~ /^(off|no)$/)
            {
                $out .= " noborder";
            }
        }
    }
    elsif (defined $$obj{border})
    {
        if (ref($$obj{border}) eq 'HASH')
        {
            $out .= " fillstyle border";
            $out .= " linecolor rgb \"$$obj{border}{color}\"" if
                (defined $$obj{border}{color});
        }
        elsif ($$obj{border} =~ /^(off|no)$/)
        {
            $out .= " noborder";
        }
    }
    return($out);
}


# Output a test image for the terminal
#
# Usage example:
# $chart = Chart::Gnuplot->new(output => "test.png");
# $chart->test;
sub test
{
    my ($self) = @_;

    my $pltTmp = "$self->{_script}";
    open(PLT, ">$pltTmp") || confess("Can't write gnuplot script $pltTmp");
    print PLT "set terminal $self->{terminal}\n";
    print PLT "set output \"$self->{output}\"\n";
    print PLT "test\n";
    close(PLT);

    # Execute gnuplot
    my $gnuplot = 'gnuplot';
    $gnuplot = $self->{gnuplot} if (defined $self->{gnuplot});
    system("$gnuplot $pltTmp");

    # Convert the image to the user-specified format
    if (defined $self->{_terminal} && $self->{_terminal} eq 'auto')
    {
        my @a = split(/\./, $self->{output});
        my $ext = $a[-1];
        &convert($self, $ext) if ($ext !~ /^e?ps$/);
    }
    return($self);
}


# Create animated gif
#
# Usage example:
# $chart->animate(
#     charts => \@charts,   # sequence of chart object
#     delay  => 10,         # delay in units of 0.01 second
# );
sub animate
{
    my ($self, %animate) = @_;
    my $charts = $animate{charts};

    # Force the terminal to be 'gif'
    # - Only the 'gif' terminal supports animation
    if (defined $self->{_terminal} && $self->{_terminal} eq 'auto')
    {
        $self->{terminal} = $self->{_terminal} = 'gif';
    }
    elsif ($self->{terminal} !~ /^gif/)
    {
        croak "animate() is supported only by the gif terminal";
    }
    $self->{terminal} .= " animate";
    $self->{terminal} .= " delay $animate{delay}" if (defined $animate{delay});

    &_setChart($self);

    open(PLT, ">>$self->{_script}") || confess("Can't write $self->{_script}");

    foreach my $chart (@$charts)
    {
        $chart->_script($self->{_script});
        $chart->_multiplot(1);

        my $plot;
        my @dataSet;
        if (defined $chart->{_dataSets2D})
        {
            $plot = 'plot';
            @dataSet = @{$chart->{_dataSets2D}};
        }
        elsif (defined $chart->{_dataSets3D})
        {
            $plot = 'splot';
            @dataSet = @{$chart->{_dataSets3D}};
        }
    
        &_setChart($chart, \@dataSet);
        open(PLT, ">>$self->{_script}") ||
            confess("Can't write $self->{_script}");
        print PLT "\n$plot ";
        print PLT join(', ', map {$_->_thaw($self)} @dataSet), "\n";
        close(PLT);
        &_reset($chart);
    }

    # Generate image file
    &execute($self);
    return($self);
}


# Change the image format
# - called by plot2d()
#
# Usage example:
# my $chart = Chart::Gnuplot->new(...);
# my $data = Chart::Gnuplot::DataSet->new(...);
# $chart->plot2d($data);
# $chart->convert('gif');
sub convert
{
    my ($self, $imgfmt) = @_;
    return($self) if (!-e $self->{output});

    # Generate temp file
    my $temp = "$self->{_script}.tmp";
    move($self->{output}, $temp);

    # Execute gnuplot
    my $convert = 'convert';
    $convert = $self->{convert} if (defined $self->{convert});

    # Rotate 90 deg for landscape image
    if (defined $self->{orient} && $self->{orient} eq 'portrait')
    {
        my $cmd = qq("$convert" $temp $temp.$imgfmt 2>&1);
        my $err = `$cmd`;
        if (defined $err && $err ne '')
        {
            die "Unsupported image format ($imgfmt)\n" if
                ($err =~ /^convert: unable to open module file/);

            my ($errTmp) = ($err =~ /^convert: (.+)/);
            die "$errTmp Perhaps the image format is not supported\n" if
                (defined $errTmp);
            die "$err\n";
        }
    }
    else
    {
        my $cmd = qq("$convert" -rotate 90 $temp $temp.$imgfmt 2>&1);
        my $err = `$cmd`;
        if (defined $err && $err ne '')
        {
            die "Unsupported image format ($imgfmt)\n" if
                ($err =~ /^convert: unable to open module file/);

            my ($errTmp) = ($err =~ /^convert: (.+)/);
            die "$errTmp Perhaps the image format is not supported\n" if
                (defined $errTmp);
            die "$err\n";
        }
    }

    # Remove the temp file
    move("$temp.$imgfmt", $self->{output});
    unlink($temp);
    return($self);
}


# Change the image format to PNG
#
# Usage example:
# my $chart = Chart::Gnuplot->new(...);
# my $data = Chart::Gnuplot::DataSet->new(...);
# $chart->plot2d($data)->png;
sub png
{
    my $self = shift;
    &convert($self, 'png');
    return($self)
}


# Change the image format to GIF
#
# Usage example:
# my $chart = Chart::Gnuplot->new(...);
# my $data = Chart::Gnuplot::DataSet->new(...);
# $chart->plot2d($data)->gif;
sub gif
{
    my $self = shift;
    &convert($self, 'gif');
    return($self)
}


# Change the image format to JPG
#
# Usage example:
# my $chart = Chart::Gnuplot->new(...);
# my $data = Chart::Gnuplot::DataSet->new(...);
# $chart->plot2d($data)->jpg;
sub jpg
{
    my $self = shift;
    &convert($self, 'jpg');
    return($self)
}


# Change the image format to PS
#
# Usage example:
# my $chart = Chart::Gnuplot->new(...);
# my $data = Chart::Gnuplot::DataSet->new(...);
# $chart->plot2d($data)->ps;
sub ps
{
    my $self = shift;
    &convert($self, 'ps');
    return($self)
}


# Change the image format to PDF
#
# Usage example:
# my $chart = Chart::Gnuplot->new(...);
# my $data = Chart::Gnuplot::DataSet->new(...);
# $chart->plot2d($data)->pdf;
sub pdf
{
    my $self = shift;
    &convert($self, 'pdf');
    return($self)
}


# Copy method of the chart object
sub copy
{
    my ($self, $num) = @_;
    my @clone = &_copy(@_);

    foreach my $clone (@clone)
    {
        my $dirTmp = tempdir(CLEANUP => 1);
        ($^O =~ /MSWin/)? ($dirTmp .= '\\'): ($dirTmp .= '/');
        $clone->{_script} = $dirTmp . "plot";
    }
    return($clone[0]) if (!defined $num);
    return(@clone);
}

################## Chart::Gnuplot::DataSet class ##################

package Chart::Gnuplot::DataSet;
use strict;
use Carp;
use File::Temp qw(tempdir);
use Chart::Gnuplot::Util qw(_lineType _pointType _fillStyle _copy);

# Constructor
sub new
{
    my ($class, %hash) = @_;

    my $dirTmp = tempdir(CLEANUP => 1);
    ($^O =~ /MSWin/)? ($dirTmp .= '\\'): ($dirTmp .= '/');
    $hash{_data} = $dirTmp . "data";

    my $self = \%hash;
    return bless($self, $class);
}


# Generic attribute methods
sub AUTOLOAD
{
    my ($self, $key) = @_;
    my $attr = our $AUTOLOAD;
    $attr =~ s/.*:://;
    return if ($attr eq 'DESTROY');        # ignore destructor
    $self->{$attr} = $key if (defined $key);
    return($self->{$attr});
}


# xdata get-set method
sub xdata
{
    my ($self, $xdata) = @_;
    return($self->{xdata}) if (!defined $xdata);

    delete $self->{points};
    delete $self->{datafile};
    delete $self->{func};
    $self->{xdata} = $xdata;
}


# ydata get-set method
sub ydata
{
    my ($self, $ydata) = @_;
    return($self->{ydata}) if (!defined $ydata);

    delete $self->{points};
    delete $self->{datafile};
    delete $self->{func};
    $self->{ydata} = $ydata;
}


# zdata get-set method
sub zdata
{
    my ($self, $zdata) = @_;
    return($self->{zdata}) if (!defined $zdata);

    delete $self->{points};
    delete $self->{datafile};
    delete $self->{func};
    $self->{zdata} = $zdata;
}


# points get-set method
sub points
{
    my ($self, $points) = @_;
    return($self->{points}) if (!defined $points);

    delete $self->{xdata};
    delete $self->{ydata};
    delete $self->{zdata};
    delete $self->{datafile};
    delete $self->{func};
    $self->{points} = $points;
}


# datafile get-set method
sub datafile
{
    my ($self, $datafile) = @_;
    return($self->{datafile}) if (!defined $datafile);

    delete $self->{xdata};
    delete $self->{ydata};
    delete $self->{zdata};
    delete $self->{points};
    delete $self->{func};
    $self->{datafile} = $datafile;
}


# func get-set method
sub func
{
    my ($self, $func) = @_;
    return($self->{func}) if (!defined $func);

    delete $self->{xdata};
    delete $self->{ydata};
    delete $self->{zdata};
    delete $self->{points};
    delete $self->{datafile};
    $self->{func} = $func;
}


# Copy method of the data set object
sub copy
{
    my ($self, $num) = @_;
    my @clone = &_copy(@_);

    foreach my $clone (@clone)
    {
        my $dirTmp = tempdir(CLEANUP => 1);
        ($^O =~ /MSWin/)? ($dirTmp .= '\\'): ($dirTmp .= '/');
        $clone->{_data} = $dirTmp . "data";
    }
    return($clone[0]) if (!defined $num);
    return(@clone);
}


# Thaw the data set object
# - call _fillStyle()
# _ call different _thaw*()
#
# TODO:
# - data file delimiter
# - data labels
sub _thaw
{
    my ($self, $chart) = @_;
    my $string;
    my $using = '';

    # Data points stored in arrays
    # - in any case, ydata need to be defined
    if (defined $self->{ydata})
    {
        my $fileTmp = $self->{_data};
        $string = "'$fileTmp'";

        # Process 3D data set
        # - zdata is defined
        if (defined $self->{zdata})
        {
            $using = (ref($self->{xdata}->[0]) eq 'ARRAY')?
                &_thawXYZGrid($self) : &_thawXYZ($self);
        }
        # Treatment for financebars and candlesticks styles
        # - Both xdata and ydata are defined
        elsif (defined $self->{xdata} && defined $self->{style} &&
            $self->{style} =~ /^(financebars|candlesticks)$/)
        {
            $using = &_thawXYFinance($self);
        }
        # Treatment for errorbars and errorlines styles
        # - Both xdata and ydata are defined
        # - Style is defined and contain "error"
        elsif (defined $self->{xdata} && defined $self->{style} &&
            $self->{style} =~ /error/)
        {
            # Error bars along x-axis
            if ($self->{style} =~ /^xerror/)
            {
                $using = &_thawXYXError($self);
            }
            # Error bars along y-axis
            elsif ($self->{style} =~ /^(y|box)error/)
            {
                $using = &_thawXYYError($self);
            }
            # Error bars along both x and y-axis
            elsif ($self->{style} =~ /^(box)?xyerror/)
            {
                $using = &_thawXYXYError($self);
            }
        }
        # Treatment for hbars
        # - use "boxxyerrorbars" style to mimic
        elsif (defined $self->{xdata} && defined $self->{style} &&
            $self->{style} eq 'hbars')
        {
            &_thawXYHbars($self);
        }
        # Treatment for hlines
        # - use "boxxyerrorbars" style to mimic
        elsif (defined $self->{xdata} && defined $self->{style} &&
            $self->{style} eq 'hlines')
        {
            &_thawXYHlines($self);
        }
        elsif (defined $self->{xdata} && defined $self->{style} &&
            $self->{style} eq 'histograms')
        {
            $using = &_thawXYHistograms($self);
        }
        # Normal x-y plot
        # - Both xdata and ydata are defined
        elsif (defined $self->{xdata})
        {
            $using = &_thawXY($self);
        }
        # Only ydata is defined
        # - Plot ydata against index
        else
        {
            # Treatment for financebars and candlesticks styles
            if (defined $self->{style} &&
                $self->{style} =~ /^(financebars|candlesticks)$/)
            {
                &_thawYFinance($self);
            }
            # Treatment for errorbars and errorlines styles
            # - Style is defined and contain "error"
            elsif (defined $self->{style} && $self->{style} =~ /^yerror/)
            {
                &_thawYError($self);
            }
            # Other plotting styles
            else
            {
                &_thawY($self);
            }
            $using = "1:2" if (defined $self->{timefmt});
        }
    }
    # Data in points
    elsif (defined $self->{points})
    {
        my $pt = $self->{points};
        my $fileTmp = $self->{_data};
        $string = "'$fileTmp'";

        # Horizontal lines plotting style
        if (defined $self->{style} && $self->{style} eq 'hlines')
        {
            &_thawPointsHLines($self);
        }
        # Horizontal bars plotting style
        elsif (defined $self->{style} && $self->{style} eq 'hbars')
        {
            &_thawPointsHBars($self);
        }
        # Horizontal bars plotting style
        elsif (defined $self->{style} && $self->{style} eq 'histograms')
        {
            $using = &_thawPointsHistograms($self);
        }
        # 3D grid data points
        elsif (ref($$pt[0][0]) eq 'ARRAY')
        {
            $using = &_thawPointsGrid($self);
        }
        else
        {
            $using = &_thawPoints($self);
        }
    }
    # File
    elsif (defined $self->{datafile})
    {
        $string = "'$self->{datafile}'";
        $string .= " every $self->{every}" if (defined $self->{every});
        $string .= " index $self->{index}" if (defined $self->{index});
    }
    # Function
    elsif (defined $self->{func})
    {
        # Parametric function
        if (ref($self->{func}) eq 'HASH')
        {
            if (defined ${$self->{func}}{z})
            {
                $string = "${$self->{func}}{x},${$self->{func}}{y},".
                    "${$self->{func}}{z}";
            }
            else
            {
                $string = "${$self->{func}}{x},${$self->{func}}{y}";
            }
        }
        else
        {
            $string = "$self->{func}";
        }
    }
    else
    {
        croak("Unknown or undefined data source");
    }

    # Process the Gnuplot "using" feature
    $using = $self->{using} if (defined $self->{using});
    $string .= " using $using" if ($using ne '');

    # Add title for the data sets
    (defined $self->{title})? ($string .= " title \"$self->{title}\""):
        ($string .= " title \"\"");

    # Change plotting style, color, width and point size
    $string .= " smooth $self->{smooth}" if (defined $self->{smooth});
    $string .= " axes $self->{axes}" if (defined $self->{axes});
    $string .= " with $self->{style}" if (defined $self->{style});
    $string .= " linetype ".&_lineType($self->{linetype}) if
        (defined $self->{linetype});
    $string .= " linecolor rgb \"$self->{color}\"" if (defined $self->{color});
    $string .= " linewidth $self->{width}" if (defined $self->{width});
    $string .= " pointtype ".&_pointType($self->{pointtype}) if
        (defined $self->{pointtype});
    $string .= " pointsize $self->{pointsize}" if (defined $self->{pointsize});
    
    # Filling style of the curve
    if (defined $self->{fill})
    {
        $string .= " fill".&_fillStyle($self->{fill});

        # Set details of the border
        if (defined $self->{border})
        {
            if (ref($self->{border}) eq 'HASH')
            {
                $string .= " border";
                $string .= " linecolor rgb \"$self->{border}{color}\"" if
                    (defined $self->{border}{color});
            }
            elsif ($self->{border} =~ /^(off|no)$/)
            {
                $string .= " noborder";
            }
        }
    }
    return($string);
}


# Process input data of array of y
sub _thawY
{
    my ($ds) = @_;
    my $ydata = $ds->{ydata};

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$ydata; $i++)
    {
        print DATA "$i $$ydata[$i]\n";
    }
    close(DATA);
}


# Process input data of array of y for plotting style "yerror..."
sub _thawYError
{
    my ($ds) = @_;
    my $ydata = $ds->{ydata};

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @{$$ydata[0]}; $i++)
    {
        print DATA "$i $$ydata[0][$i]";
        for (my $j = 1; $j < @$ydata; $j++)
        {
            print DATA " $$ydata[$j][$i]";
        }
        print DATA "\n";
    }
    close(DATA);
}


# Process input data of array of y for plotting financial time series
sub _thawYFinance
{
    my ($ds) = @_;
    my $ydata = $ds->{ydata};

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @{$$ydata[0]}; $i++)
    {
        print DATA "$i $$ydata[0][$i] $$ydata[1][$i] ".
            "$$ydata[2][$i] $$ydata[3][$i]\n";
    }
    close(DATA);
}


# Process input data of array of x and y
sub _thawXY
{
    my ($ds) = @_;

    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};
    croak("x-data and y-data have unequal length") if
        (scalar(@$ydata) != scalar(@$xdata));

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$xdata; $i++)
    {
        print DATA "$$xdata[$i] $$ydata[$i]\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my @a = split(/\s+/, $$xdata[0]);
        my $yCol = scalar(@a) + 1;
        $using = "1:$yCol";
    }
    return($using);
}


# Process input data of array of x and y for plotting style "xerror..."
sub _thawXYXError
{
    my ($ds) = @_;

    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};
    croak("x-data and y-data have unequal length") if
        (scalar(@{$$xdata[0]}) != scalar(@$ydata));

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$ydata; $i++)
    {
        print DATA "$$xdata[0][$i] $$ydata[$i]";
        for (my $j = 1; $j < @$xdata; $j++)
        {
            print DATA " $$xdata[$j][$i]";
        }
        print DATA "\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my ($xTmp) = (ref($$xdata[0]) eq 'ARRAY')? ($$xdata[0][0]):
            ($$xdata[0]);
        my @a = split(/\s+/, $xTmp);
        my $yCol = scalar(@a) + 1;
        $using = "1:$yCol";
    }
    return($using);
}


# Process input data of array of x and y for plotting style "yerror..."
sub _thawXYYError
{
    my ($ds) = @_;

    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};
    croak("x-data and y-data have unequal length") if
        (scalar(@{$$ydata[0]}) != scalar(@$xdata));

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$xdata; $i++)
    {
        print DATA "$$xdata[$i] $$ydata[0][$i]";
        for (my $j = 1; $j < @$ydata; $j++)
        {
            print DATA " $$ydata[$j][$i]";
        }
        print DATA "\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my ($xTmp) = (ref($$xdata[0]) eq 'ARRAY')? ($$xdata[0][0]):
            ($$xdata[0]);
        my @a = split(/\s+/, $xTmp);
        my $yCol = scalar(@a) + 1;
        $using = "1:$yCol";
    }
    return($using);
}


# Process input data of array of x and y for plotting style "xyerror..."
sub _thawXYXYError
{
    my ($ds) = @_;

    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    if (scalar(@$xdata) == scalar(@$ydata))
    {
        for (my $i = 0; $i < @{$$xdata[0]}; $i++)
        {
            print DATA "$$xdata[0][$i] $$ydata[0][$i]";
            for (my $j = 1; $j < @$ydata; $j++)
            {
                print DATA " $$xdata[$j][$i] $$ydata[$j][$i]";
            }
            print DATA "\n";
        }
    }
    else
    {
        for (my $i = 0; $i < @{$$xdata[0]}; $i++)
        {
            print DATA "$$xdata[0][$i] $$ydata[0][$i]";
            if (scalar(@$xdata) == 2)
            {
                my $ltmp = $$xdata[0][$i] - $$xdata[1][$i]*0.5;
                my $htmp = $$xdata[0][$i] + $$xdata[1][$i]*0.5;
                print DATA " $ltmp $htmp ".
                    "$$ydata[1][$i] $$ydata[2][$i]\n";
            }
            else
            {
                my $ltmp = $$ydata[0][$i] - $$ydata[1][$i]*0.5;
                my $htmp = $$ydata[0][$i] - $$ydata[1][$i]*0.5;
                print DATA " $$xdata[1][$i] $$xdata[2][$i] ".
                    "$ltmp $htmp\n";
            }
        }
    }
    close(DATA);
    
    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my ($xTmp) = (ref($$xdata[0]) eq 'ARRAY')? ($$xdata[0][0]):
            ($$xdata[0]);
        my @a = split(/\s+/, $xTmp);
        my $yCol = scalar(@a) + 1;
        $using = "1:$yCol";
    }
    return($using);
}


# Process input data of array of x and y for plotting financial time series
sub _thawXYFinance
{
    my ($ds) = @_;

    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};
    croak("x-data and y-data have unequal length") if
        (scalar(@{$$ydata[0]}) != scalar(@$xdata));

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$xdata; $i++)
    {
        print DATA "$$xdata[$i] $$ydata[0][$i] $$ydata[1][$i] ".
            "$$ydata[2][$i] $$ydata[3][$i]\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my @a = split(/\s+/, $$xdata[0]);
        my $yCol = scalar(@a) + 1;
        $using = "1:".join(':', ($yCol .. $yCol+3));
    }
    return($using);
}


# Process input data of arrays of x and y for plottiny style "hlines"
sub _thawXYHlines
{
    my ($ds) = @_;
    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$xdata; $i++)
    {
        print DATA "0 $$ydata[$i] 0 $$xdata[$i] $$ydata[$i] ".
            "$$ydata[$i]\n";
    }
    close(DATA);
    $ds->{style} = "boxxyerrorbars";
}


# Process input data of arrays of x and y for plottiny style "hbars"
sub _thawXYHbars
{
    my ($ds) = @_;
    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};

    # Put the corrdinates in a hash
    my %points;
    for (my $i = 0; $i < @$xdata; $i++)
    {
        $points{$$xdata[$i]} = $$ydata[$i];
    }

    # Sort x and y according to y values
    my (@sortX, @sortY) = ();
    foreach my $sx (sort {$points{$a} <=> $points{$b}} keys %points)
    {
        push(@sortX, $sx);
        push(@sortY, $points{$sx});
    }

    my $ylow = my $yhigh = $sortY[0];
    if (scalar(@sortY) > 1)
    {
        $ylow = 0.5*(3*$sortY[0]-$sortY[1]);
        $yhigh = 0.5*(3*$sortY[-1]-$sortY[-2]);
    }

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$xdata; $i++)
    {
        $ylow = 0.5*($sortY[$i]+$sortY[$i-1]) if ($i > 0);
        $yhigh = ($i < $#sortY)?
            0.5*($sortY[$i]+$sortY[$i+1]) :
            2.0*$sortY[$i] - $ylow;
        print DATA "0 $sortY[$i] 0 $sortX[$i] $ylow $yhigh\n";
    }
    close(DATA);
    $ds->{style} = "boxxyerrorbars";
}


# Process input data of arrays of x and y for plottiny style "histograms"
sub _thawXYHistograms
{
    my ($ds) = @_;
    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};
    croak("x-data and y-data have unequal length") if
        (scalar(@$ydata) != scalar(@$xdata));
    my $using;

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    if (ref($$ydata[0]) eq 'ARRAY')
    {
        for (my $i = 0; $i < @$xdata; $i++)
        {
            print DATA "\"$$xdata[$i]\" " . join(' ', @{$$ydata[$i]}) . "\n";
        }
        $using = join(':', (2 .. scalar(@{$$ydata[0]})+1)) . ":xticlabels(1)";
    }
    else
    {
        for (my $i = 0; $i < @$xdata; $i++)
        {
            print DATA "\"$$xdata[$i]\" $$ydata[$i]\n";
        }
        $using = "2:xticlabels(1)";
    }
    close(DATA);

    return($using);
}


# Process input data of array of x, y and z
sub _thawXYZ
{
    my ($ds) = @_;

    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};
    my $zdata = $ds->{zdata};
    croak("x-data and y-data have unequal length") if
        (scalar(@$ydata) != scalar(@$xdata));
    croak("y-data and z-data have unequal length") if
        (scalar(@$ydata) != scalar(@$zdata));

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$xdata; $i++)
    {
        print DATA "$$xdata[$i] $$ydata[$i] $$zdata[$i]\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my @a = split(/\s+/, $$xdata[0]);
        my $yCol = scalar(@a) + 1;
        $using = "1:$yCol";

        my @b = split(/\s+/, $$ydata[0]);
        my $zCol = scalar(@b) + $yCol;
        $using .= ":$zCol";
    }
    return($using);
}


# Process input data of matrice of x, y and z
sub _thawXYZGrid
{
    my ($ds) = @_;

    my $xdata = $ds->{xdata};
    my $ydata = $ds->{ydata};
    my $zdata = $ds->{zdata};
    croak("x-data and y-data have unequal length") if
        (scalar(@$ydata) != scalar(@$xdata));
    croak("y-data and z-data have unequal length") if
        (scalar(@$ydata) != scalar(@$zdata));

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$xdata; $i++)
    {
        for (my $j = 0; $j < @{$$xdata[$i]}; $j++)
        {
            print DATA "$$xdata[$i][$j] $$ydata[$i][$j] $$zdata[$i][$j]\n";
        }
        print DATA "\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my @a = split(/\s+/, $$xdata[0][0]);
        my $yCol = scalar(@a) + 1;
        $using = "1:$yCol";

        my @b = split(/\s+/, $$ydata[0][0]);
        my $zCol = scalar(@b) + $yCol;
        $using .= ":$zCol";
    }
    return($using);
}


# Process input data of array of points
sub _thawPoints
{
    my ($ds) = @_;

    # Write data into temp file
    my $pt = $ds->{points};
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$pt; $i++)
    {
        print DATA join(" ", @{$$pt[$i]}), "\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my $col = 1;
        $using = "1";
        for (my $i = 0; $i < @{$$pt[0]}-1; $i++)
        {
            my @a = split(/\s+/, $$pt[0][$i]);
            $col += scalar(@a);
            $using .= ":$col";
        }
    }
    return($using);
}


# Process input data of array of points for plotting style "hlines"
sub _thawPointsHLines
{
    my ($ds) = @_;
    confess("Data/time input data is not supported in hlines plotting style")
        if (defined $ds->{timefmt});

    # Write data into temp file
    my $pt = $ds->{points};
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");

    # hlines plotting style
    for (my $i = 0; $i < @$pt; $i++)
    {
        print DATA "0 $$pt[$i][1] 0 $$pt[$i][0] $$pt[$i][1] $$pt[$i][1]\n";
    }

    $ds->{style} = "boxxyerrorbars";
    close(DATA);
}


# Process input data of array of points for plotting style "hbars"
sub _thawPointsHBars
{
    my ($ds) = @_;
    confess("Data/time input data is not supported in hbars plotting style")
        if (defined $ds->{timefmt});

    my $pt = $ds->{points};

    # Put the corrdinates in a hash
    my %points;
    for (my $i = 0; $i < @$pt; $i++)
    {
        $points{$$pt[$i][0]} = $$pt[$i][1];
    }

    # Sort x and y according to y values
    my (@sortX, @sortY) = ();
    foreach my $sx (sort {$points{$a} <=> $points{$b}} keys %points)
    {
        push(@sortX, $sx);
        push(@sortY, $points{$sx});
    }

    my $ylow = my $yhigh = $sortY[0];
    if (scalar(@sortY) > 1)
    {
        $ylow = 0.5*(3*$sortY[0]-$sortY[1]);
        $yhigh = 0.5*(3*$sortY[-1]-$sortY[-2]);
    }

    # Write data into temp file
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$pt; $i++)
    {
        $ylow = 0.5*($sortY[$i]+$sortY[$i-1]) if ($i > 0);
        $yhigh = ($i < $#sortY)?
            0.5*($sortY[$i]+$sortY[$i+1]) :
            2.0*$sortY[$i] - $ylow;
        print DATA "0 $sortY[$i] 0 $sortX[$i] $ylow $yhigh\n";
    }
    close(DATA);

    $ds->{style} = "boxxyerrorbars";
    close(DATA);
}


# Process input data of array of points for plotting histograms
sub _thawPointsHistograms
{
    my ($ds) = @_;

    # Write data into temp file
    my $pt = $ds->{points};
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    my $numCol = scalar(@{$$pt[0]});
    for (my $i = 0; $i < @$pt; $i++)
    {
        print DATA "\"$$pt[$i][0]\" ", join(' ', @{$$pt[$i]}[1 .. $numCol-1]),
            "\n";
    }
    close(DATA);

    my $using = join(':', (2 .. $numCol)) . ":xticlabels(1)";
    return($using);
}


# Process input data of a matrix of points
sub _thawPointsGrid
{
    my ($ds) = @_;

    # Write data into temp file
    my $pt = $ds->{points};
    my $fileTmp = $ds->{_data};
    open(DATA, ">$fileTmp") || confess("Can't write data to temp file");
    for (my $i = 0; $i < @$pt; $i++)
    {
        for (my $j = 0; $j < @{$$pt[$i]}; $j++)
        {
            print DATA join(" ", @{$$pt[$i][$j]}), "\n";
        }
        print DATA "\n";
    }
    close(DATA);

    # Construst using statement for date-time data
    my $using = '';
    if (defined $ds->{timefmt})
    {
        my $col = 1;
        $using = "1";
        for (my $i = 0; $i < @{$$pt[0][0]}-1; $i++)
        {
            my @a = split(/\s+/, $$pt[0][0][$i]);
            $col += scalar(@a);
            $using .= ":$col";
        }
    }
    return($using);
}


# Curve fitting method
#
# NOTICE: This feature is experimental and in alpha phase.
#
# Usage example:
# my $dataSet = Chart::Gnuplot::DataSet->new(...);
#
# my $dataFit = $dataSet->fit(
#    func => "a*x + b",                # linear fit
#    vars => 'x',
#    params => {a => -1, b => 0.5},    # seed
# );
#
# print "a = $dataFit->{params}->{a}\n";
# print "b = $dataFit->{params}->{b}\n";
#
# # Plot the raw data set and fitted curve
# $chart->plot2d($dataSet, $dataFit);
sub fit
{
    my ($self, %hash) = @_;
    my $script = my $data = my $result = my $log = $self->{_data};
    my $styleTmp = (defined $self->{style})? $self->{style} : 'lines';

    # Filename of the temp files
    $script =~ s/\/data$/\/fit\.script/;
    $result =~ s/\/data$/\/fit\.result/;
    $log =~ s/\/data$/\/fit\.log/;

    # Prepare parameter and error string for printing
    my $paraString = my $paraList = my $errList = '';
    my @params = ();
    my $paraRef = ref($hash{params});
    if ($paraRef eq 'HASH')
    {
        @params = keys %{$hash{params}};
        my @err = ();
        my $parFile = $self->{_data};
        $parFile =~ s/\/data$/\/par\.dat/;
        open(PARA, ">$parFile") || confess "Can't write parameter to $parFile";
        foreach my $pTmp (@params)
        {
            my $vTmp = (defined ${$hash{params}}{$pTmp})?
                ${$hash{params}}{$pTmp} : 1.0;
            print PARA "$pTmp = $vTmp\n";
            push(@err, $pTmp . "_err");
        }
        close(PARA);
        $paraString = "\"$parFile\"";
        $paraList = join(',', @params);
        $errList = join(',', @err);
    }
    elsif ($paraRef eq 'ARRAY')
    {
        @params = @{$hash{params}};
        my @err = map {$_ . '_err'} @params;
        $paraString = $paraList = join(',', @params);
        $errList = join(',', @err);
    }
    else
    {
        @params = split(/,\s*/, $hash{params});
        my @err = map {$_ . '_err'} @params;
        $paraString = $paraList = $hash{params};
        $errList = join(',', @err);
    }

    if (!defined $hash{using})
    {
        my @col = split(/\s*,\s*/, $hash{vars});
        my $numCol = scalar(@col) + 1;
        if (ref($self->{ydata}->[0]) eq 'ARRAY')
        {
            $numCol++;
            $self->{style} = 'yerror';    # temp style for data file generation
        }
        $hash{using} = join(':', (1 .. $numCol));
    }
    $self->_thaw() if (!-e $data);    # generate data file
    $self->{style} = $styleTmp;

    # Generate gnuplot script for curve fitting
    open(FIT, ">$script") || confess("Can't generate script to $script");
    print FIT "set fit logfile \"$log\" errorvariables\n";
    print FIT "set print \"$result\"\n";
    print FIT "fit $hash{func} \"$data\" using $hash{using}".
        " via $paraString\n";
    print FIT "print $paraList\n";
    print FIT "print $errList\n";
    close(FIT);

    # Call gnuplot
    system("gnuplot $script >& /dev/null");

    # Read and parse the result file
    open(RES, $result) || confess("Can't read fitting result $result");
    chomp(my ($pLine, $eLine) = <RES>);
    close(RES);

    # Save the result in DataSet object
    my %param;
    my @pVal = split(/\s+/, $pLine);
    my @eVal = split(/\s+/, $eLine);
    my $fitted = '';
    for (my $i = 0; $i < @pVal; $i++)
    {
        $param{$params[$i]} = $pVal[$i];
        $param{$params[$i]."_err"} = $eVal[$i];
        $fitted .= "$params[$i] = $pVal[$i],";
    }

    $fitted .= $hash{func};
    my $outDS = Chart::Gnuplot::DataSet->new(
        func   => $fitted,
        params => \%param,
    );
    return($outDS);
}


1;

__END__

=head1 NAME

Chart::Gnuplot - Plot graph using Gnuplot in Perl on the fly

=head1 SYNOPSIS

    use Chart::Gnuplot;
    
    # Data
    my @x = (-10 .. 10);
    my @y = (0 .. 20);
    
    # Create chart object and specify the properties of the chart
    my $chart = Chart::Gnuplot->new(
        output => "fig/simple.png",
        title  => "Simple testing",
        xlabel => "My x-axis label",
        ylabel => "My y-axis label",
        ....
    );
    
    # Create dataset object and specify the properties of the dataset
    my $dataSet = Chart::Gnuplot::DataSet->new(
        xdata => \@x,
        ydata => \@y,
        title => "Plotting a line from Perl arrays",
        style => "linespoints",
        ....
    );
    
    # Plot the data set on the chart
    $chart->plot2d($dataSet);
    
    ##################################################
    
    # Plot many data sets on a single chart
    $chart->plot2d($dataSet1, $dataSet2, ...);

=head1 DESCRIPTION

This Perl module is to plot graphs uning GNUPLOT on the fly. In order to use
this module, gnuplot need to be installed. If image format other than PS and
EPS is required to generate, it is recommended to install the convert program
of ImageMagick as well. Please refer to L<MECHANISM OF THIS MODULE> for
details.

To plot chart using Chart::Gnuplot, a chart object and at least one dataset
object are required. Information about the chart such as output file, chart
title, axes labels and so on is specified in the chart object.  Dataset object
contains information about the dataset to be plotted, including source of the
data points, dataset label, color used to plot and more.

After chart object and dataset object(s) are created, the chart can be plotted
using the L<plot2d>, L<plot3d> or L<multiplot> method of the chart object, e.g.

    # $chart is the chart object
    $chart->plot2d($dataSet1, $dataSet2, ...);

To illustate the features of Chart::Gnuplot, the best way is to show by
examples. A lot of examples can be found in SourceForge
L<http://chartgnuplot.sourceforge.net>.

=head1 MECHANISM OF THIS MODULE

Casual users may skip this session.

When the plotting method (e.g. L<plot2d>) is called, Chart::Gnuplot would
generate a Gnuplot script based on the information in the chart object and
dataset object. Then it would call the Gnuplot program. Unless specified
explicitly in L<terminal> of the Chart object, Chart::Gnuplot would by default
generate the image in PS format first and then convert the image (by
ImageMagick) based on the extension of the filename. The rationale of this
approach is that the postscript terminal is so far the best developed teriminal
and so this would let users to enjoy the power of Gnuplot as much as possible.

Because the default terminal is postscript, if ImageMagick is not installed,
you would always need to specify the L<terminal> if the output format is not PS
(or EPS).

On the other hand, for some image formats, e.g. mousing supported SVG, which
ImageMagick cannot be converted to, the terminal must be set explicitly (e.g.,
C<svg mousing> in this case).

=head1 CHART OBJECT

The chart object can be initiated by the c<new> method. Properties of the chart
may be specified optionally when the object is initiated:

    my $chart = Chart::Gnuplot->new(%options);

=head2 Chart Options

=head3 output

Output file of the graph. E.g.

    output => "fig/chart.png",

By default, the image format is detected automatically by the extension of the
filename. (Please refer to L<MECHANISM OF THIS MODULE> for details). However,
it can also be changed manually by the L<terminal> option or the format
conversion methods such as L<convert> and L<png>.

Some of image formats that can be detected automatically are:

    bmp  : Microsoft Windows bitmap
    epdf : Encapsulated Portable Document Format
    epi  : Encapsulated PostScript Interchange format
    eps  : Encapsulated PostScript
    gif  : Graphics Interchange Format
    jpg  : Joint Photographic Experts Group JFIF format
    pdf  : Portable Document Format
    png  : Portable Network Graphics
    ppm  : Portable Pixmap Format
    ps   : PostScript file
    psd  : Adobe Photoshop bitmap file
    xpm  : X Windows system pixmap

If the filename has no extension, postscipt format will be output.

=head3 title

Title of the chart. E.g.,

    title => "Chart title"

Properties of the chart title can be specified in hash. E.g.,

    title => {
        text => "Chart title",
        font => "arial, 20",
        ....
    }

Supported properties are:

    text     : title in plain text
    font     : font face (and optionally font size)
    color    : font color
    offset   : offset relative to the default position
    enhanced : title contains subscript/superscipt/greek? (on/off)

Default values would be used for properties not specified. These properties has
no effect on the main title of the multi-chart (see L<multiplot>).

=head3 xlabel, ylabel, zlabel

Label of the x-axis, y-axis and z-axis. E.g.

    xlabel => "Bottom axis label"

Properties of the axis label can be specified in hash, similar to the chart
title. Supported properties are:

    text     : title in plain text
    font     : font face (and optionally font size)
    color    : font color
    offset   : offset relative to the default position
    rotate   : rotation in degrees
    enhanced : title contains subscript/superscipt/greek? (on/off)

=head3 x2label, y2label

Label of the secondary x-axis (displayed on the top of the graph) and the
secondary y-axis (displayed on the right of the graph). See L<xlabel>.

=head3 xrange, yrange, zrange

Range of the x-axis, y-axis and z-axis in the plot, e.g.

    xrange => [0, "pi"]

would make the plot from x = 0 to x = 3.14159...

=head3 x2range, y2range

Range of the secondary (top horizontal and right vertical) axes of the plot.
See L<xrange, yrange, zrange>.

=head3 trange, urange, vrange

Range of the parametric parameter (t for 2D plots, while u and v for 3D plots).
See L<xrange, yrange, zrange>.

=head3 xtics, ytics, ztics

The tics and tic label on the x-axis, y-axis and z-axis. E.g.

   xtics => {
      labels   => [-10, 15, 20, 25],
      labelfmt => "%3f",
      ....
   }

If you set this to C<undef>. E.g.,

    xtics => undef

Then this option will be explicitly I<unset> and the chart will have not have
tic marks on the specified axis.

Supported properties are:

    labels    : the locations of the tic labels
    start     : the starting value for manually-specified range
	incr      : the increment for manually-specified range
	end       : the ending value for manually-specified range
    labelfmt  : format of the labels
    font      : font of the labels
    fontsize  : font size of the lebals
    fontcolor : font color of the label
    offset    : position of the tic labels shifted from its default
    rotate    : rotation of the tic labels
    length    : length of the tics
    along     : where the tics are put (axis/border)
    minor     : number of minor tics between adjacant major tics
    mirror    : turn on and off the tic label of the secondary axis. No effect
              : for C<ztics> (on/off)

=head3 x2tics, y2tics

The tics and tic label of the secondary axes. See L<xtics, ytics, ztics>.

=head3 legend

Legend describing the plots. Supported properties are:

    position : position of the legend
    width    : number of character widths to be added or subtracted to the
             : region of the legend
    height   : number of character heights to be added or subtracted to the
             : region of the legend
    align    : alignment of the text label. Left or right (default)
    order    : order of the keys
    title    : title of the legend
    sample   : format of the sample lines
    border   : border of the legend
    
See L<border> for the available options of border

E.g.

    legend => {
       position => "outside bottom",
       width    => 3,
       height   => 4,
       align    => "right",
       order    => "horizontal reverse",
       title    => "Title of the legend",
       sample   => {
           length   => 3,
           position => "left",
           spacing  => 2,
       },
       border   => {
           linetype => 2,
           width    => 1,
           color    => "blue",
       },
    }

=head3 timeaxis

Specify the axes of which the tic labels are date/time string. Possible values
are combinations of "x", "y", "x2", and "y2" joined by ",". E.g.

    timeaxis => "x, y2"

means that the x-axis and y2-axis are data/time axes.

=head3 border

Border of the graph. Properties supported are:

    sides    : sides on which border is displayed
    linetype : line type
    width    : line width
    color    : line coler

E.g.

    border => {
        sides    => "bottom, left",
        linetype => 3,
        width    => 2,
        color    => '#ff00ff',
    }

C<sides> tells which side(s) will be displayed. Default is all four borders for
2D plots, and four bottom and left vertial borders for 3D plots. Acceptable
valurs are the 12-bit code (see the Gnuplot manual) or the following names:

    bottom
    left
    top
    right
    bottom left front
    bottom left back
    bottom right front
    bottom right back
    left vertical
    right vertical
    front vertical
    back vertical
    top left front
    top left back
    top right front
    top right back

If you set this to C<undef>. E.g.,

    border => undef

Then this option will be explicitly I<unset> and the chart will have not have
any border.

=head3 grid

Major grid lines. E.g.

    grid => {
        linetype => 'dash',
        width    => 2,
        ....
    }

Supported properties are:

    linetype : line type of the grid lines (default: dot)
    width    : line width (defaulr: 0)
    color    : line color (default: black)
    xlines   : whether the vertical grid lines are drawn (on/off)
    ylines   : whether the horizontal grid lines are drawn (on/off)

=head3 tmargin, bmargin

Top and bottom margin (in character height). This option has no effect in 3D
plots. E.g.

    tmargin => 10

=head3 lmargin, rmargin

Left amd right margin (in character width). This option has no effect in 3D
plots. See L<tmargin, bmargin>.

=head3 orient

Orientation of the image. Possible values are "lanscape" (default) and
"portrait". E.g.

    orient => "portrait"

=head3 imagesize

Size (length and height) of the image relative to the default. E.g.

    imagesize => "0.8, 0.5"

=head3 size

Size of the plot relative to the chart size. This is useful in some
multi-plot such as inset chart. E.g.

    size => "0.5, 0.4"

=head3 origin

Origin of the chart. This is useful in some multi-plot such as inset chart.
E.g.

    origin => "0.1, 0.5"

=head3 timestamp

Time stamp of the plot. To place the time stamp with default setting,

    timestamp => 'on'

Properties of the time stamp (such as date-time format) can also be set, e.g.

    timestamp => {
       fmt    => '%d/%m/%y %H:%M',
       offset => "10,-3",
       font   => "Helvetica",
    }

Supported properties are:

    fmt    : date-time format
    offset : offset relative to the default position
    font   : font face (and optionally font size)

=head3 bg

Background color of the chart. This option has no effect in the sub-chart of
multiplot. E.g. to give the chart a yellow background,

    bg => "yellow"

Properties can be specified in hash. E.g.,

    bg => {
        color   => "yellow",
        density => 0.2,
    }

Supported properties are:

    color   : color (name ot RRGGBB value)
    density : density of the coloring

=head3 plotbg

Background color of the plot area. This option has no effect in 3D plots. See
L<bg> for supported properties.

=head3 gnuplot

The path of Gnuplot executable. This option is useful if you are using Windows
or have multiple versions of Gnuplot installed. E.g.,

    gnuplot => "C:\Program Files\...\gnuplot\bin\wgnuplot.exe"   # for Windows

=head3 convert

The path of convert executable of ImageMagick. This option is useful if you
have multiple convert executables.

=head3 terminal

The terminal driver that Gnuplot uses. E.g.,

    terminal => 'svg mousing'

The default value is C<postscript enhanced color>. Terminal is not necessarily
related to the output image format. E.g., you may use gif terminal and then
convert the image format to jpg by the L<convert()> method.

=head2 Chart Options Not Mentioned Above

If Chart::Gnuplot encounters options not mentions above, it would convert them
to Gnuplot set statements. E.g. if the chart object is

    $chart = Chart::Gnuplot->new(
        ...
        foo => "FOO",
    );

the generated Gnuplot statements would be:

    ...
    set foo FOO

This mechanism lets Chart::Gnuplot support many features not mentioned above
(such as "cbrange", "samples", "view" and so on).

=head2 Chart Methods

=head3 new

    my $chart = Chart::Gnuplot->new(%options);

Constructor of the chart object. If no option is specified, default values
would be used. See L<Chart Options> for available options.

=head3 set

General set methods for arbitrary number of options.

    $chart->set(%options);

E.g.

    $chart->set(view => '30,60');

will be translated to the Gnuplot statement

    set view 30,60

=head3 plot2d

    $chart->plot2d(@dataSets);

Plot the data sets in a 2D chart. Each dataset is represented by a dataset
object.

=head3 plot3d

    $chert->plot3d(@dataSets);

Plot the data sets in a 3D chart. Each dataset is represented by a dataset
object.

=head3 multiplot

    $chart->multiplot(@charts);

Plot multiple charts in the same image.

=head3 animate

Create animated gif. E.g.

    # Create (main) chart object
    my $chart = Chart::Gnuplot->new(
        output => "animate.gif",
    );

    # Add frames to the (main) chart object
    my $T = 30; # number of frames
    my @c;
    for (my $i = 0; $i < $T; $i++)
    {
        $c[$i] = Chart::Gnuplot->new(xlabel => 'x');
        my $ds = Chart::Gnuplot::DataSet->new(
            func => "sin($i*2*pi/$T + x)",
        );
        $c[$i]->add2d($ds);
    }

    # Create animation
    $chart->animate(
        charts => \@c,
        delay  => 10,   # delay 0.1 sec between successive images
    );

Supported properties are:

    charts : chart sequence used to create the animation
    delay  : delay (in units of 0.01 second) between successive images, default
           : value is 5

See L<add2d> and L<add3d>.

=head3 add2d

Add a 2D dataset to a chart without plotting it out immediately. Used with
C<multiplot> or C<animate>.

=head3 add3d

Add a 3D dataset to a chart without plotting it out immediately. Used with
C<multiplot> or C<animate>.

=head3 label

Add an arbitrary text label. e.g.,

    $chart->label(
        text       => "This is a label",
        position   => "0.2, 3 left",
        offset     => "2,2",
        rotate     => 45,
        font       => "arial, 15",
        fontcolor  => "dark-blue",
        pointtype  => 3,
        pointsize  => 5,
        pointcolor => "blue",
    );

Supported properties are:

    text       : label text
    position   : position of the label
    offset     : offset relative to the default position
    rotate     : rotation in degrees
    font       : font face (and optionally font size)
    fontcolor  : color of the text
    pointtype  : point type
    pointsize  : point size
    pointcolor : point color

=head3 arrow

Draw arbitrary arrow. e.g.,

    $chart->arrow(
        from     => "0,2",
        to       => "0.3,0.1",
        linetype => 'dash',
        width    => 2,
        color    => "dark-blue",
        head     => {
            size  => 2,
            angle => 30,
        },
    );

Supported properties are:

    from     : starting position
    to       : ending position (position of the arrow head)
    rto      : ending position relative to the starting position
    linetype : line type
    width    : line width
    color    : color
    head     : arrow head

Supported properties of the arrow head are:

    size      : size of the head
    angle     : angle (in degree) between the arrow and the head branch
    direction : head direction ('back', 'both' or 'off')

=head3 line

Draw arbitrary straight line. e.g.,

    $chart->line(
        from     => "0,2",
        to       => "0.3,0.1",
        linetype => 'dash',
        width    => 2,
        color    => "dark-blue",
    );

Supported properties are:

    from     : starting position
    to       : ending position (position of the arrow head)
    rto      : ending position relative to the starting position
    linetype : line type
    width    : line width
    color    : color

=head3 rectangle

Draw arbitrary rectangle. e.g.,

    $chart->rectangle(
        from => "screen 0.2, screen 0.2",
        to   => "screen 0.4, screen 0.4",
        fill => {
            density => 0.2,
            color   => "#11ff11",
        },
        border    => {color => "blue"},
        linewidth => 3,
        layer     => 'front',
        index     => 1,
    );

Most properties of a rectangle can be classified into location, dimension,
filling and border. Location and dimension of the rectangle can be specified by
C<from> and C<to>, or C<from> and C<rto>, or C<at>, C<width> and C<height>.
Filling can be specified by C<color> and C<density>, or C<pattern>. Border has
only one property C<color> so far. Besides, C<linewidth> controls the line
width of the border as well as the filling pattern. The layer that the
rectangle is drawn is set by C<layer>. The C<index> is a tag of the rectangle,
which usually can be omitted.

=head3 ellipse

Draw arbitrary ellipse. e.g.,

    $chart->ellipse(
        at     => "screen 0.2, screen 0.2",
        width  => 0.2,
        height => 0.5
        fill   => {pattern => 2},
        border => {color => "blue"},
    );

The properties of C<ellipse> is the same as those of L<rectangle>, except that
its location and dimension must be set by C<at>, C<width> and C<height>.

=head3 circle

Draw arbitrary circle. e.g.,

    $chart->circle(
        at    => "screen 0.2, screen 0.2",
        size  => 0.5
        fill  => {pattern => 2},
        layer => 'behind',
    );

The properties of C<circle> is the same as those of L<rectangle>, except that
its location and dimension must be set by C<at>, C<width> and C<height>.

=head3 polygon

Draw arbitrary polygon. e.g.,

    $chart->polygon(
        vertices => [
            " 0,  0.2",
            "-2, -0.2",
            {to  => "2, -0.3"},
            {rto => "0, 0.3"},
        ],
        fill   => {pattern => 2},
        border => {color => "blue"},
    );

The location and dimension of the polygon are specified by an array of
C<vertices>. Except C<border>, C<pattern> of C<fill>, C<index> and C<layer>,
other properties of rectangle is not supported.

=head3 copy

Copy the chart object. This method is especially useful when you want to copy a
chart with highly customized format. E.g.

    my $chart = Chart::Gnuplot->new(
        ...
    );

    # $copy is a copy of $chart
    my $copy = $chart->copy;

You may also make multiple copies . E.g.

    my @copies = $chart->copy(10);  # make 10 copies

=head3 convert

Convert the image format by ImageMagick, e.g.

    $chart->convert('png');

=head3 png

    $chart->png;

Change the image format to PNG.

=head3 gif

    $chart->gif;

Change the image format to GIF.

=head3 jpg

    $chart->jpg;

Change the image format to JPEG.

=head3 ps

    $chart->ps;

Change the image format to postscript.

=head3 pdf

    $chart->pdf

Change the image format to PDF.

=head3 command

    $chart->command($gnuplotCommand);

Add a gnuplot command. This method is useful for the Gnuplot features that have
not yet implemented.

    $chart->command(\@gnuplotCommands);

Add a list of gnuplot commands.

=head3 execute

Execute Gnuplot. Normally users do not need to call this method directly
because this method would be called automatically by other methods such as
L<plot2d>, L<multiplot> and L<animate>.

=head1 DATASET OBJECT

The dataset object can be initiated by the C<new> method. Properties of the
dataset may be specified optionally when the object is initiated:

    my $dataset = Chart::Gnuplot::DataSet->new(%options);

The data source of the dataset can be specified by either one of the following
ways:

=over

=item 1. Arrays of x values, y values and z values (in 3D plots) of the data
points.

=item 2. Array of data points. Each point is specified as an array of x, y, z
coordinates

=item 3. Data file.

=item 4. Mathematical expression (for a function).

=back

=head2 Dataset Options

=head3 xdata, ydata, zdata

The x, y, z values of the data points. E.g.

    xdata => \@x

If C<xdata> is omitted but C<ydata> is defined, the integer index starting from
0 would be used for C<xdata>.

=head3 points

Data point matrix of the format [[x1,y1], [x2,y2], [x3,y3], ...]

    points => \@points

=head3 datafile

Input data file

    datafile => $file

The data files are assumed to be space-separated, with each row corresponding
to one data point. Lines beginning with "#" are considered as comments and
would be ignored. Other formats are not supported at this moment.

=head3 func

Mathematical function to be plotted. E.g.

    func => "sin(x)*x**3"

Supported functions:

    abs(x)       : absolute value
    acos(x)      : inverse cosine
    acosh(x)     : inverse hyperbolic cosine
    arg(x)       : complex argument
    asin(x)      : inverse sine
    asinh(x)     : inverse hyperbolic sine
    atan(x)      : inverse tangent
    atanh(x)     : inverse hyperbolic tangent
    besj0(x)     : zeroth order Bessel function of the first kind
    besj1(x)     : first order Bessel function of the first kind
    besy0(x)     : zeroth order Bessel function of the second kind
    besy1(x)     : first order Bessel function of the second kind
    ceil(x)      : ceiling function
    cos(x)       : cosine
    cosh(x)      : hyperbolic cosine
    erf(x)       : error function
    erfc(x)      : complementary error function
    exp(x)       : expontial function
    floor(x)     : floor function
    gamma(x)     : gamma function
    ibeta(a,b,x) : incomplete beta function
    inverf(x)    : inverse error function
    igamma(a,x)  : incomplete gamma function
    imag(x)      : imaginary part
    invnorm(x)   : inverse normal distribution function
    int(x)       : integer part
    lambertw(x)  : Lambert W function
    lgamma(x)    : log gamma function
    log(x)       : natural logarithm
    log10(x)     : common logarithm
    norm(x)      : normal distribution function
    rand(x)      : pseudo random number
    real(x)      : real part
    sgn(x)       : sign function
    sin(x)       : sine
    sinh(x)      : hyperbolic sine
    sqrt(x)      : square root
    tan(x)       : tangent
    tanh(x)      : hyperbolic tangent

Please see the Gnuplot manual for updated information.

Supported mathematical constants:

    pi : the circular constant 3.14159...

Supported arithmetic operators:

    addition           : +
    division           : /
    exponentiation     : **
    factorial          : !
    modulo             : %
    multiplication     : *
    subtraction        : -, e.g., 1-2
    unary minus        : -, e.g., -1

Supported logical operations:

    and                      : &&
    complement               : ~
    equality                 : ==
    greater than             : >
    greater than or equal to : >=
    inequality               : !=
    less than                : <
    less than or equal to    : <= 
    negation                 : !
    or                       : ||
    if ... than else ...     : ?:, e.g., a ? b : c

Parametric functions may be represented as hash. E.g.

    func => {x => 'sin(t)', y => 'cos(t)'}

will draw a circle.

=head3 title

Title of the dataset (shown in the legend).

=head3 style

The plotting style for the dataset, including

    lines          : join adjacent points by straight lines
    points         : mark each points by a symbol
    linespoints    : both "lines" and "points"
    dots           : dot each points. Useful for large datasets
    impluses       : draw a vertical line from the x-axis to each point
    steps          : join adjacent points by steps
    boxes          : draw a centered box from the x-axis to each point
    xerrorbars     : "dots" with horizontal error bars
    yerrorbars     : "dots" with vertical error bars
    xyerrorbars    : both "xerrorbars" and "yerrorbars"
    xerrorlines    : "linespoints" with horizontal error bars
    yerrorlines    : "linespoints" with vertical error bars
    xyerrorlines   : both "xerrorlines" and "yerrorlines"
    boxerrorbars   : "boxes" with "yerrorbars"
    boxxyerrorbars : use rectangles to represent the data with errors
    financebars    : finance bars for open, high, low and close price
    candlesticks   : candle sticks for open, high, low and close price
    hbars          : horizontal bars (experimental)
    hlines         : horizontal lines (experimental)
    vectors        : arrows
    circles        : circles, for say, bubble charts
    histograms     : for plotting histograms

C<hbars> and C<hlines> are available only if the data is input from C<points>
or C<(x,y)data>.

=head3 color

Color of the dataset in the plot. Can be a named color or RBG (#RRGGBB) value.
The supported color names can be found in the file F<doc/colors.txt> in the
distribution. E.g.

    color => "#99ccff"

is equivalent to

    color => "dark-red"

=head3 width

Line width used in the plot. The default width is 1.

=head3 linetype

Line type. Can be an integer or line type name. The supported line type names
can be found in the file F<doc/linetypes.txt> in the distribution. E.g.

    linetype => 3

is equivalent to

    linetype => 'dash'

Note: the line type may not be displayed as the name if C<terminal> is set and
is not postscript.

=head3 pointtype

Point type. Can be an integer or point type name. The supported point type
names can be found in the file F<doc/pointtypes.txt> in the distribution. E.g.

    pointtype => 64

is equivalent to

    pointtype => 'square'

Note: the point type may not be displayed as the name if C<terminal> is set and
is not postscript.

=head3 pointsize

Point size of the plot. E.g.

    pointsize => 3

The default point size is 1.

=head3 fill

Filling the boxes. Has effect only on plotting styles with boxes, such as
"boxes", "boxxyerrorbars" and "financebars". To fill with pattern,

    fill => {
        pattern => 1,
    }

C<pattern> may be an interger from 0 (no filling) to 7.

To fill with solid,

    fill => {
        color   => '#33bb33',
        density => 0.2,
    }

C<color> may be named color or RGB (#RRGGBB). C<density> may be a real number
from 0 (empty) to 1.

=head3 border

Border of the boxes. Has effect only on plotting styles with boxes and if
C<fill> is set. C<color> (either named color or RGB) is the only supported
property. E.g.

    border => {
        color => 'blue',
    }

=head3 axes

Axes used in the plot. Possible values are "x1y1", "x1y2", "x2y1" and "x2y2".

=head3 timefmt

Time format of the input data. The valid format are:

    %d : day of the month, 1-31
    %m : month of the year, 1-12
    %y : year, 2-digit, 0-99
    %Y : year, 4-digit
    %j : day of the year, 1-365
    %H : hour, 0-24
    %M : minute, 0-60
    %s : seconds since the Unix epoch (1970-01-01 00:00 UTC)
    %S : second, 0-60
    %b : name of the month, 3-character abbreviation
    %B : name of the month

=head3 smooth

The smooth method used in plotting data points. Supported methods include cubic
splines (csplines), Bezier curve (bezier) and other. Please see Gnuplot manual
for details.

=head3 using

The C<using> keyword of Gnuplot.

=head3 every

The C<every> keyword of Gnuplot. Has effect only if the data is input from
C<datafile>.

=head3 index

The C<index> keyword of Gnuplot. Has effect only if the data is input from
C<datafile>.

=head2 Dataset Methods

=head3 new

    my $dataset = Chart::Gnuplot::DataSet->new(%options);

Constructor of the dataset object. If no option is specified, default values
would be used. See L<Dataset Options> for available options.

=head3 copy

Copy the dataset object. This method is especially useful when you want to copy
a dataset with highly customized format. E.g.

    my $dataset = Chart::Gnuplot::DataSet->new(
        ...
    );

    # $copy and $dataset will have the same format and contain the same data
    my $copy = $dataset->copy;

You may also make multiple copies . E.g.

    my @copies = $dataset->copy(10);  # make 10 copies

=head1 EXAMPLES

Some simple examples are shown below. Many more come with the distribution.

=over

=item 1. Plot a mathematical expression

    my $chart = Chart::Gnuplot->new(
        output => "expression.png"
    );

    my $dataSet = Chart::Gnuplot::DataSet->new(
        func => "sin(x)"
    );

    $chart->plot2d($dataSet);

=item 2. Plot from two Perl arrays, one for the x-axis data and the other the
y-axis.

    my $chart = Chart::Gnuplot->new(
        output => "arrays.png"
    );

    my $dataSet = Chart::Gnuplot::DataSet->new(
        xdata => \@x,
        ydata => \@y,
    );

    $chart->plot2d($dataSet);

=item 3. Plot x-y pairs

    # Data
    my @xy = (
        [1.1, -3],
        [1.2, -2],
        [3.5,  0],
        ...
    );

    my $chart = Chart::Gnuplot->new(
        output => "points.png"
    );

    my $dataSet = Chart::Gnuplot::DataSet->new(
        points => \@xy
    );

    $chart->plot2d($dataSet);

=item 4. Plot data from a data file

    my $chart = Chart::Gnuplot->new(
        output => "file.png"
    );

    my $dataSet = Chart::Gnuplot::DataSet->new(
        datafile => "in.dat"
    );

    $chart->plot2d($dataSet);

=item 5. Chart title, axis label and legend

    # Chart object
    my $chart = Chart::Gnuplot->new(
        output => "trigonometric.gif",
        title  => "Three basic trigonometric functions",
        xlabel => "angle in radian",
        ylabel => "function value"
    );

    # Data set objects
    my $sine = Chart::Gnuplot::DataSet->new(
        func  => "sin(x)",
        title => "sine function"
    );
    my $cosine = Chart::Gnuplot::DataSet->new(
        func  => "cos(x)",
        title => "cosine function"
    );
    my $tangent = Chart::Gnuplot::DataSet->new(
        func  => "tan(x)",
        title => "tangent function"
    );

    $chart->plot2d($sine, $cosine, $tangent);

=item 6. Title in non-English characters (Thanks to WOLfgang Schricker)

    use Encode;

    my $title = ...   # Title with German umlauts
    $title = decode("utf8", $title);

    Chart::Gnuplot->new(
        encoding => 'iso-8859-1',
        title    => $title,
    );

=item 7. Plot a financial time series

    my $chart = Chart::Gnuplot->new(
        output   => "dj.ps",
        title    => "Dow-Jones Index time series",
        timeaxis => 'x',
        xtics    => {
            labelfmt => '%b%y',
        },
    );

    my $dow = Chart::Gnuplot::DataSet->new(
        file    => "dj.dat",
        timefmt => '%Y-%m-%d',      # time format of the input data
        style   => "candlesticks",
        grid    => 'on',
    );

    $chart->plot2d($dow);

=item 8. Plot several graphs on the same image

    my $chart = Chart::Gnuplot->new(
        output => "multiplot.gif",
    );

    my $left = Chart::Gnuplot->new();
    my $sine = Chart::Gnuplot::DataSet->new(
        func  => "sin(x)",
    );
    $left->add2d($sine);

    my $center = Chart::Gnuplot->new();
    my $cosine = Chart::Gnuplot::DataSet->new(
        func  => "cos(x)",
    );
    $center->add2d($cosine);

    my $right = Chart::Gnuplot->new();
    my $tangent = Chart::Gnuplot::DataSet->new(
        func  => "tan(x)",
    );
    $right->add2d($tangent);

    # Place the Chart::Gnuplot objects in matrix to indicate their locations
    $chart->multiplot([
        [$left, $center, $right]
    ]);

=back

=head1 WISH LIST

=over

=item 1. Improve the manual.

=item 2. Add curve fitting method.

=item 3. Improve the testsuite.

=item 4. Reduce number of temporary files generated.

=back

=head1 REQUIREMENTS

L<Carp>, L<File::Copy>, L<File::Temp>, L<Storable>

Gnuplot L<http://www.gnuplot.info>

ImageMagick L<http://www.imagemagick.org> (for full feature)

=head1 SEE ALSO

Gnuplot official website L<http://www.gnuplot.info>

=head1 AUTHOR

Ka-Wai Mak <kwmak@cpan.org>

=head1 COPYRIGHT

Copyright (c) 2008-2011, 2013-2015 Ka-Wai Mak. All rights reserved.

=head1 LICENSE

This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.

=cut