I'm also sure that gnuplot can do it. Gnuplot reads plotting instructions from a text file, and data from comma or whitespace separated files, both are pretty easy to generate with Perl.

Gnuplot happily reads both plotting instructions and data from stdin, allowing you to just open a pipe to gnuplot and generate plots without having to create intermediate files.

I haven't used them, but there are even (Perl) programs that are geared towards driving gnuplot for streaming data:

• driveGnuPlots
• feedgnuplot

Also i see in GD::Graph two_axes option but it can be used only with two data sets

Not so. From the GD::Graph docs:

two_axes

Use two separate axes for the first and second data set. The first data set will be set against the left axis, the second against the right axis. If more than two data sets are being plotted, the use_axis option should be used to specify which data sets use which axis.

Note that if you use this option, that you need to use y1_label and y2_label, instead of just y_label, if you want the two axes to have different labels. The same goes for some other options starting with the letter 'y' and an underscore.

Default: 0.

use_axis

If two y-axes are in use and more than two datasets are specified, set this option to an array reference containing a value of 1 or 2 (for the left and right scales respectively) for each dataset being plotted. That is, to plot three datasets with the second on a different scale than the first and third, set this to [1,2,1]<.

Default: [1,2].

An example:

#! perl -slw
use strict;
use GD::Graph::lines;


my @data = (
    [ 1 .. 10 ],
    [ map{    -5 + int rand   40 } 1 .. 10 ],
    [ map{ -5000 + int rand 7000 } 1 .. 10 ],
    [ map{    -5 + int rand   40 } 1 .. 10 ],
    [ map{ -5000 + int rand 7000 } 1 .. 10 ],
);

my $graph = GD::Graph::lines->new( 1000, 600 );

$graph->set(
    two_axes => 1,
    use_axis => [ 1,2,1,2 ],
);

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

open IMG, '>:raw', 'multiline.png' or die $!;
print IMG $gd->png;
close IMG;

system 'multiline.png';
[download]

It is still not representing the 2nd and 4th datasets on other y-axis. I couldn't see the second y axis appearing on the right.

It is still not representing the 2nd and 4th datasets on other y-axis.

Really.

I couldn't see the second y axis appearing on the right.

What do you see?

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