PDL::Graphics::PGPLOT - PGPLOT enhanced interface for PDL
perldl> $a = pdl [1..100] perldl> $b = sqrt($a) perldl> line $b perldl> hold Graphics on HOLD perldl> $c = sin($a/10)*2 + 4 perldl> line $c
PDL::Graphics::PGPLOT is an interface to the PGPLOT graphical libraries.
Current display commands:
imag - Display an image (uses pgimag()/pggray() as appropriate) ctab - Load an image colour table line - Plot vector as connected points points - Plot vector as points errb - Plot error bars cont - Display image as contour map bin - Plot vector as histogram ( e.g. C<bin(hist($data))> ) hi2d - Plot image as 2d histogram (not very good IMHO...) poly - Draw a polygon vect - Display 2 images as a vector field
Device manipulation commands:
hold - Hold current plot window range - allows overlays etc. release - Release back to autoscaling of new plot window for each command rel - short alias for 'release' env - Define a plot window, put on 'hold' dev - Explicitly set a new PGPLOT graphics device
The actual PGPLOT module is loaded only when the first of these commands is executed.
Notes: $transform for image/cont etc. is used in the same way as the TR() array in the underlying PGPLOT FORTRAN routine but is, fortunately, zero-offset.
For completeness: The transformation array connect the pixel index to a world coordinate such that:
X = tr[0] + tr[1]*i + tr[2]*j Y = tr[3] + tr[4]*i + tr[5]*j
In general variables are passed to the pgplot routines by using get_dataref to get the reference to the values. Before passing to pgplot routines however, the data are checked to see if they are in accordance with the format (typically dimensionality) required by the PGPLOT routines. This is done using the routine checkarg (internal to PGPLOT.) This routine checks the dimensionality of the input data. If there are superfluous dimensions of size 1 they will be trimmed away until the dimensionality is correct. Example:
get_dataref
checkarg
Assume a piddle with dimensions (1,100,1,1) is passed to C<line>, which expects its inputs to be vectors. C<checkarg> will then return a piddle with dimensions (100). If instead the same piddle was passed to C<imag>, which requires 2D piddles as output, C<checkarg> would return a piddle with dimensionality (100, 1) (Dimensions are removed from the I<start>)
Thus, if you want to provide support for another PGPLOT function, the structure currently look like this (there are plans to use the Options package to simplify the options parsing):
($arg, $opt)=_extract_hash(@_); # Extract the hash(es) on the commandline <Check the number of input parameters> <deal with $arg> checkarg($x, 3); # For a hypothetical 3D routine. ... pgcube($n, $x->get_dataref); 1;
All routines in this package take a hash with options as an optional input. This options hash can be used to set parameters for the subsequent plotting without going via the PGPLOT commands.
This is implemented such that the plotting settings (such as line width, line style etc.) are affected only for that plot, any global changes made, say, with pgslw() are preserved.
The following options are always parsed. Whether they have any importance depend on the routine invoked - line style is irrelevant for imag and so on. This is indicated in the help text for the commands below.
The options are not case sensitive and will match for unique substrings, but this is not encouraged as obscure options might invalidate what you thought was a unique substring.
In the listing below examples are given of each option. The actual option can then be used in a plot command by specifying it as an argument to the function wanted. (It can be placed anywhere in the command list).
E.g: $opt={COLOR=>2}; line $x, $y, $opt; # This will plot a line with red color
This options allows you to set the arrow shape, and optionally size for arrows for the vect routine. The arrow shape is specified as a hash with the key FS to set fill style, ANGLE to set the opening angle of the arrow head, VENT to set how much of the arrow head is cut out and SIZE to set the arrowsize.
The following
$opt = {ARROW => {FS=>1, ANGLE=>60, VENT=>0.3, SIZE=>5}};
will make a broad arrow of five times the normal size.
Alternatively the arrow can be specified as a set of numbers corresponding to an extention to the syntax for pgsah. The equivalent to the above is
$opt = {ARROW => pdl([1, 60, 0.3, 5})};
For the latter the arguments must be in the given order, and if any are not given the default values of 1, 45, 0.3 and 1.0 respectively will be used.
The arrowsize can be specified separately using this option to the options hash. It is useful if an arrowstyle has been set up and one wants to plot the same arrow with several sizes.
$opt = {ARROWSIZE => 2.5};
Set the character/symbol size as a multiple of the standard size.
$opt = {CHARSIZE => 1.5}
Set the colour to be used for the subsequent plotting. This can be specified as a number, and the most used colours can also be specified with name, according to the following table (note that this only works for the default colour map):
0 - WHITE 1 - BLACK 2 - RED 3 - GREEN 4 - BLUE 5 - CYAN 6 - MAGENTA 7 - YELLOW 8 - ORANGE 14 - DARKGRAY 16 - LIGHTGRAY
Set the fill type to be used for pgpoly/pgrect/pgcirc. The fill can either be specified using numbers or name, according to the following table, where the recognised name is shown in capitals - it is case- insensitive, but the whole name must be specified.
1 - SOLID 2 - OUTLINE 3 - HATCHED 4 - CROSS_HATCHED $opt = {FILLTYPE => 'SOLID'};
(see below for an example of hatched fill)
Set the character font. This can either be specified as a number following the PGPLOT numbering or name as follows (name in capitals): 1 - NORMAL 2 - ROMAN 3 - ITALIC 4 - SCRIPT
(Note that in a string, the font can be changed using the escape sequences \fn, \fr, \fi and \fs respectively)
$opt = {FONT => 'ROMAN'};
gives the same result as
$opt = {FONT => 2};
Set the hatching to be used if either fillstyle 3 or 4 is selected (see above) The specification is similar to the one for specifying arrows. The arguments for the hatching is either given using a hash with the key ANGLE to set the angle that the hatch lines will make with the horizontal, SEPARATION to set the spacing of the hatch lines in units of 1% of min(height, width) of the view surface, and PHASE to set the offset the hatching. Alternatively this can be specified as a 1x3 piddle $hatch=pdl[$angle, $sep, $phase].
$opt = {FILLTYPE => 'HATCHED', HATCHING => {ANGLE=>30, SEPARATION=>4}};
Can also be specified as
$opt = {FILL=> 'HATCHED', HATCH => pdl [30,4,0.0]};
See also the documentation for poly for another example of hatching.
Set the line style. This can either be specified as a number following the PGPLOT numbering (1 - SOLID line, 2 - DASHED, 3 - DOT-DASH-dot-dash, 4 - DOTTED, 5 - DASH-DOT-DOT-dot) or using name (as given in capitals above). Thus the following two specifications both specify the line to be dotted:
$opt = {LINESTYLE => 4}; $varopt = {LINESTYLE => 'DOTTED'};
The names are not case sensitive, but the full name is required.
Set the line width. It is specified as a integer multiple of 0.13 mm.
$opt = {LINEWIDTH => 10}; # A rather fat line
A more detailed listing of the functions and their usage follows. For all functions we specify which options take effect and what other options exist for the given function.
Open PGPLOT graphics device
Usage: dev $device, [$nx,$ny];
$device is a PGPLOT graphics device such as "/xserve" or "/ps", if omitted defaults to last used device (or value of env var PGPLOT_DEV if first time). $nx, $ny specify sub-panelling.
Display an image (uses pgimag()/pggray() as appropriate)
Usage: imag ( $image, [$min, $max, $transform], [$opt] )
Options recognised:
MIN - Sets the minimum value to be used for calculation of the display stretch MAX - Sets the maximum value for the same TRANSFORM - The transform 'matrix' as a 6x1 vector for display None of the standard options are relevant here
Load an image colour table
Usage:
ctab ( $name, [$contrast, $brightness] ) # Builtin col table ctab ( $ctab, [$contrast, $brightness] ) # $ctab is Nx4 array ctab ( $levels, $red, $green, $blue, [$contrast, $brightness] )
Currently no options are implemented for this command.
Plot vector as connected points
Usage: line ( [$x,] $y, [$opt] ) Options recognised: The following standard options influence this command: COLO(U)R, LINESTYLE, LINEWIDTH
$x = sequence(10)/10.; $y = sin($x)**2; line $x, $y, {COLOR => 'RED', LINESTYLE=>3}; # Draw a red dot-dashed line
Plot vector as points
Usage: points ( [$x,] $y, [$symbol(s)], [$opt] ) Options recognised: SYMBOL - Either a piddle with the same dimensions as $x, containing the symbol associated to each point or a number specifying the symbol to use for every point, or a name specifying the symbol to use according to the following (recognised name in capital letters): 0 - SQUARE 1 - DOT 2 - PLUS 3 - ASTERISK 4 - CIRCLE 5 - CROSS 7 - TRIANGLE 8 - EARTH 9 - SUN 11 - DIAMOND 12- STAR PLOTLINE - If this is >0 a line will be drawn through the points. The following standard options influence this command: CHARSIZE, COLOUR, LINESTYLE, LINEWIDTH
$y = sequence(10)**2+random(10); # Plot blue stars with a solid line through: points $y, {PLOTLINE => 1, COLOUR => BLUE, SYMBOL => STAR};
Plot error bars (using pgerrb())
errb ( $y, $yerrors, [$opt] ) errb ( $x, $y, $yerrors, [$opt] ) errb ( $x, $y, $xerrors, $yerrors, [$opt] ) errb ( $x, $y, $xloerr, $xhierr, $yloerr, $yhierr, [$opt]) Options recognised: TERM - Length of terminals in multiples of the default length SYMBOL - Plot the datapoints using the symbol value given, either as name or number - see documentation for 'points' The following standard options influence this command: CHARSIZE, COLOUR, LINESTYLE, LINEWIDTH
$y = sequence(10)**2+random(10); $sigma=0.5*sqrt($y); errb $y, $sigma, {COLOUR => RED, SYMBOL => 18};
Display image as contour map
Usage: cont ( $image, [$contours, $transform, $misval], [$opt] )
Options recognised: CONTOURS - A piddle with the contour levels FOLLOW - Follow the contour lines around (uses pgcont rather than pgcons) If this is set >0 the chosen linestyle will be ignored and solid line used for the positive contours and dashed line for the negative contours. LABELS - An array of strings with labels for each contour LABELCOLOUR - The colour of labels if different from the draw colour This will not interfere with the setting of draw colour using the colour keyword. MISSING - The value to ignore for contouring NCONTOURS - The number of contours wanted for automatical creation, overridden by CONTOURS TRANSFORM - The pixel-to-world coordinate transform vector The following standard options influence this command: COLOUR, LINESTYLE, LINEWIDTH
$x=sequence(10,10); $ncont = 4; $labels= ['COLD', 'COLDER', 'FREEZING', 'NORWAY'] cont $x, {NCONT => $ncont, LABELS => $labels, LABELCOLOR => RED, COLOR => BLUE} # This will give four blue contour lines labelled in red.
Plot vector as histogram ( e.g. bin(hist($data)) )
bin(hist($data))
Usage: bin ( [$x,] $data ) Options recognised: The following standard options influence this command: COLOUR, LINESTYLE, LINEWIDTH
Plot image as 2d histogram (not very good IMHO...)
Usage: hi2d ( $image, [$x, $ioff, $bias], [$opt] ) Options recognised: IOFFSET - The offset for each array slice. >0 slants to the right <0 to the left. BIAS - The bias to shift each array slice up by. None of the standard options influence this command. Note that meddling with the ioffset and bias often will require you to change the default plot range somewhat. It is also worth noting that if you have TriD working you will probably be better off using mesh3d or a similar command - see 'help TriD'
$r=sequence(100)/50-1.0; $y=exp(-$r**2)*transpose(exp(-$r**2)) hi2d $y, {IOFF => 1.5, BIAS => 0.07};
Draw a polygon
Usage: poly ( $x, $y )
Options recognised: The following standard options influence this command: COLOUR, LINESTYLE, LINEWIDTH, FILLTYPE, HATCHING
# Fill with hatching in two different colours $x=sequence(10)/10; # First fill with cyan hatching poly $x, $x**2, {COLOR=>5, FILL=>3}; hold; # Then do it over again with the hatching offset in phase: poly $x, $x**2, {COLOR=>6, FILL=>3, HATCH=>{PHASE=>0.5}}; release;
Display 2 images as a vector field
Usage: vect ( $a, $b, [$scale, $pos, $transform, $misval] )
This routine will plot a vector field. $a is the horizontal component and $b the vertical component.
Options recognised: SCALE - Set the scale factor for vector lengths. POS - Set the position of vectors. <0 - vector head at coordinate >0 - vector base at coordinate =0 - vector centered on the coordinate TRANSFORM - The pixel-to-world coordinate transform vector MISSING - Elements with this value are ignored. The following standard options influence this command: ARROW, ARROWSIZE, CHARSIZE, COLOUR, LINESTYLE, LINEWIDTH
$a=rvals(11,11,{Centre=>[5,5]}); $b=rvals(11,11,{Centre=>[0,0]}); vect $a, $b, {COLOR=>YELLOW, ARROWSIZE=>0.5, LINESTYLE=>dashed};
Karl Glazebrook [kgb@aaoepp.aao.gov.au] modified by Jarle Brinchmann (jarle@ast.cam.ac.uk), docs mangled by Tuomas J. Lukka (lukka@fas.harvard.edu) and Christian Soeller (c.soeller@auckland.ac.nz).
All rights reserved. There is no warranty. You are allowed to redistribute this software / documentation under certain conditions. For details, see the file COPYING in the PDL distribution. If this file is separated from the PDL distribution, the copyright notice should be included in the file.
To install PDL, copy and paste the appropriate command in to your terminal.
cpanm
cpanm PDL
CPAN shell
perl -MCPAN -e shell install PDL
For more information on module installation, please visit the detailed CPAN module installation guide.