Hi, here is a start for you.

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

#my @data = (
#    ["1st","2nd","3rd","4th","5th","6th","7th", "8th", "9th"],
#    [    3,   4,   14,   30,   12,    8,    7,    20,    15],
#    [    2,   8,    2,    5,    3,  1,    3,     4,     1],


my @data = (
    ["1st","2nd","3rd","4th","5th","6th","7th", "8th", "9th"],
    [    3,   4,   14,   '',   '',    '',    7,    20,    15],
    [    '',   '',    '',    5,    3,  1,    3,     4,     1],



#    [    5,   12,   24,   33,   19,    8,    6,    15,    21],
#    [    1,    2,    5,    6,    3,  1.5,    1,     3,     4],
);
#sets 3,4 will overwrite second y label 


my $my_graph = new GD::Graph::mixed( );
$my_graph->set(
        transparent => '0',
        x_label => 'X Label',
        y1_label => 'Y1 label',
        y2_label => 'Y2 label',
    title => 'Using two axes',
        y1_max_value => 40,
        y2_max_value => 8,
        y_tick_number => 8,
        y_label_skip => 2,
        long_ticks => 1,
    use_axis => [1,2,1,2],
        legend_placement => 'BR',
        x_labels_vertical => 1,
        x_label_position => 1/2,
        two_axes => 1,
    legend_marker_width => 100,
    
    l_margin            => 10,
    b_margin            => 10,
    r_margin            => 20,
    t_margin            => 10,
    show_values         => 1,

);


$my_graph->set_legend( 'X', 'XY', 'diff-X/XY', '95%XY');
#$my_graph->set_legend( 'X', 'XY');

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

open(IMG, ">$0.png") or die "$!\n";
binmode IMG;
print IMG $gd->png;
close IMG;
[download]

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