I don't know how much control you have over the software on the server you have, but you might want to check out Gnuplot , which is a more full featured graphing program. Check out the demo galleries for the different versions.

GD is great, but limited in flexibility; but someone may find a solution for you.

As for myself, I always reach for a Tk canvas to do graphing, on which I can do all sorts of tricks and export it to a graphic file. However, this requires an X server running.... a real drawback on a cgi server.

Here is a way to use Arrays of Arrays to plot multiple data sets with GD 

#!/usr/bin/perl
use warnings;
use strict;
use GD;
use GD::Graph::lines;

my @data = ( [1, 2, 3, 4, 5, 6, 7, 8, 9,],
[ 8, 8.25, 8.5, 8.35, 8.76, 8.21, 8.6, 8.8, 8.5],
[ 57.4, 57.6, 57.8, 57.9, 57.4, 58.5, 57, 57.87, 58.34] );

my $my_graph = new GD::Graph::lines (600, 400);

$my_graph->set(
title => "My Graph",
    transparent   => '0',
    bgclr         => 'lgray',
    boxclr        => 'white',
    fgclr         => 'white',
    title         => 'Some simple graph',
    x_label => 'X axis label',
    y1_label => 'Y1 axis label',
    y2_label => 'Y2 axis label',
    #boxclr => '#C0C0C0',
    two_axes => 1,
);

$my_graph->set_legend("data set 1", "data set 2");

my $gd = $my_graph->plot(\@data) or die $my_graph->error;
open(IMG, ">$0.png") or die $!;
binmode IMG;
print IMG $gd->png;
close IMG;

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I'm not really a human, but I play one on earth. Cogito ergo sum a bum

In reply to Re: Issues graphing multiple data sets on the same graph in GD::Graph by zentara
in thread Issues graphing multiple data sets on the same graph in GD::Graph by SoaponaRope

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