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SLOYD / Alt-Data-Frame-ButMore-0.004_001 / lib / Data / Frame / Indexer.pm 

            

              
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package Data::Frame::Indexer;
# ABSTRACT: Function interface for indexer
use Data::Frame::Setup;
use Types::PDL qw(Piddle1D);
use Data::Frame::Indexer::ByIndex;
use Data::Frame::Indexer::ByLabel;
use Data::Frame::Types qw(:all);
use Data::Frame::Util qw(is_discrete);
use parent qw(Exporter::Tiny);
our @EXPORT_OK   = qw(loc iloc);
our %EXPORT_TAGS = ( all => \@EXPORT_OK );
my $NumericIndices =
  Piddle0Dor1D->where( sub { $_->type ne 'byte' and not is_discrete($_) } );
fun _as_indexer ($fallback_indexer_class) {
    return sub {
        my $x = @_ > 1 ? \@_ : ( $_[0] // [] );
        unless ( Ref::Util::is_ref($x) ) {
            $x = [$x];
        }
        return $x if ( Indexer->check($x) );
        if ( $NumericIndices->check($x) ) {
            return Data::Frame::Indexer::ByIndex->new( indexer => $x->unpdl );
        }
        $fallback_indexer_class->new( indexer => $x );
    };
}
*loc  = _as_indexer('Data::Frame::Indexer::ByLabel');
*iloc = _as_indexer('Data::Frame::Indexer::ByIndex');
1;
__END__
=pod
=encoding UTF-8
=head1 NAME
Data::Frame::Indexer - Function interface for indexer
=head1 VERSION
version 0.004_001
=head1 DESCRIPTION
A basic feature needed in a data frame library is the ability of subsetting
a data frame by either numeric indices or string labels of columns and rows.
Because of the ambiguity of number and string in Perl, there needs a way to 
allow user to explicitly specify whether their indexer is by numeric
indices or string labels. This modules provides functions that serves this
purpose. 
=head1 FUNCTIONS
=head2 loc($x)
Returns either undef or an indexer object, by trying below rules,
=over 4
=item *
If called with no arguments or if the argument is undef, return undef.
=item *
If the argument is an indexer object, just return it.
=item *
If the argument is a PDL of numeric types, create an indexer object
of L<Data::Frame::Indexer::ByIndex> 
=item *
Fallbacks to create an indexer object of
L<Data::Frame::Indexer::ByLabel>.
=back
=head2 iloc($x)
Similar to C<loc> but would fallback to an indexer object of
L<Data::Frame::Indexer::ByIndex>.
=head1 AUTHORS
=over 4
=item *
Zakariyya Mughal <zmughal@cpan.org>
=item *
Stephan Loyd <sloyd@cpan.org>
=back
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2014, 2019 by Zakariyya Mughal, Stephan Loyd.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut