GD::Graph::histogram - Histogram plotting module for Perl5

  use GD::Graph::histogram;

GD::Graph::histogram extends the GD::Graph module to create histograms. The module allow creation of count or percentage histograms.

Fill an array with all the data values that are to be plotted. Note that GD::Graph::histogram unlike the other GD::Graph modules can only plot one data set at a time.

	$data = [1,5,7,8,9,10,11,3,3,5,5,5,7,2,2];

Create the graph

	my $graph = new GD::Graph::histogram(400,600);

Set graph options

	$graph->set( 
		x_label         => 'X Label',
		y_label         => 'Count',
		title           => 'A Simple Count Histogram Chart',
		x_labels_vertical => 1,
		bar_spacing     => 0,
		shadow_depth    => 1,
		shadowclr       => 'dred',
		transparent     => 0,
	) 
	or warn $graph->error;

plot the graph

	my $gd = $graph->plot($data) or die $graph->error;

save the graph to a file

	open(IMG, '>histogram.png') or die $!;
	binmode IMG;
	print IMG $gd->png;

GD::Graph::histogram supports all the methods support by GD::Graph. Please refer to the GD::Graph documentation for more information.

The only method that behaves differently is plot

The plot method provided by GD::Graph::histogram expects a reference to an array of numbers.

Based on the input data, GD::Graph::histogram will generate the appropriate labels for the X axis. The X axis label represent the center point of the range of each histogram bin.

GD::Graph::histogram supports all the options supported by GD::Graph::bars. Please refer to the GD::Graph documentation for more information.

The two additional options that are specific to GD::Graph::histogram are:

	histogram_bins
		Specify the number of histogram bins to bucket the data into.
		The default is for the module to automatically computed the
		histogram bins based on the data.

	histogram_type
		Can be set to either 'percentage' or 'count'. By default the module
		will create 'count' histograms.

As with all Modules for Perl: Please stick to using the interface. If you try to fiddle too much with knowledge of the internals of this module, you could get burned. I may change them at any time.

	Snehanshu Shah
	perl@whizdog.com
	http://www.whizdog.com

Thanks for all the feedback, bug reports and bug fixes

Martin Corley Jonathan Barber William Miller

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

The full text of the license can be found in the LICENSE file included with this module.

perl(1), GD::Graph