NAME

Chart::Manual::Workflows - different ways to create charts

OVERVIEW

Four of the five major steps in creating a chart image are fixed in their order. First you have to load the module, secondly create create the object. After that you may change some properties. And always as a last step you create the image, no matter if the output goes to STDOUT or into a file.

The only flexibility lies in how you prefer to provide the data. And here you have three options. Most commonly you add one data set at the time, which could be also understood as a row of the complete data table. Second option is to build the table column by column. Thirdly you can drop the complete table at once, either by reference to a data structure or a file containing the data. The last option is closed if you already given the object data. It is not advisable to reuse a chart object for further image creation outside of modern art projects.

STEPS

Most steps are already explained elsewhere and the OVERVIEW just links there. The missing bits are layed out here.

use Chart

As with any other Modul you have to:

use Chart::[Type];

Type being a placeholder for a name of a chart type, which are: Bars, Composite, Direction, ErrorBars, HorizontalBars, Lines, LinesPoints, Mountain, Pareto, Pie, Points, Split, StackedBars. To know more about them read Chart::Manual::Types.

Alternatively write to load all chart types at ones with

use Chart;

Both are not importing any symbols in your name space but load Carp and GD.

drop data

All the methods listed in the last section, that create the final image, take as an optional, second argument data. This data may be delivered either as a reference to an array of arrays:

my $data = [ [ 1, 4, 3 ... <data set 0> ], [ <data set 1> ], ... ];
$graph->png( 'file.png', $data );

or in form of a file. Then the argument has to be a file name or a file handle (old school as in FILE or modern as in $FH). Alternatively use the method add_datafile.

data files

Are arbitrary named text files containing one or several rows of numbers, which have to be separated by spaces or tabs (\t) (mixing allowed). Perl style comments or empty lines will be ignored, but rows containing different amount of numbers will cause problems.

create image

Currently we support only images in the PNG and JPEG format. The methods to create them are named straight forwardly: ->png and ->jpeg. Both take the same arguments and produce image files. For shell scripting or web programming you need the image binary, which you get with: ->cgi_png or ->cgi_jpeg. Some users might even want the GD object for further processing by your perl programm. In that case please use: ->scalar_png or ->scalar_jpeg.

After having created a chart for web purposes, you also might want to utilize imagemap_dump.

COPYRIGHT & LICENSE

Copyright 2022 Herbert Breunung.

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

AUTHOR

Herbert Breunung, <lichtkind@cpan.org>