Can't call method "png" on an undefined value at _graph_test.pl line 9
+1, <STDIN> line 1.
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my (@h,@c);
push @h, $_->{'hour'} foreach(@{$data});
push @c, $_->{'count'} foreach(@{$data});
my $new = [ \@h, \@c];
print (\@new);


#@data=(["1st","2nd","3rd"],
#        [9,4,7]);


#  I have a hash table with $data[$index]{'hour'} and $data[$index]{'c
+ount'}
#
$graph= GD::Graph::lines->new(400,300);
$graph->set(
    x_label => 'Hour',
    y_label => 'Transaction Volume',
    title => 'Number of transactions per hour',
    y_max_value => 20,
    y_label_skip => 1,
    y_tick_number => 1);

    #$gd = $graph->plot(\@data);

    open (IMG,'>file.png') or die $!;
    binmode IMG;
    print IMG $graph->plot(\@new)->png;

    close IMG;
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because $new is an array reference, so all you need to do is fill it in as $graph->plot($new)->png;

Still getting the same error with the follwing line as the only change.

    print IMG $graph->plot($new)->png;
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$new is a already a reference to an array consisting of two arrayrefs. There is no such thing (yet) as @new in the code snippet you've posted. Try it with

print IMG $graph->plot($new)->png;
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(instead of the \@new you have there now) and see what happens.

use strict should have caught this. You *are* using, strict, aren't you?

Philosophy can be made out of anything. Or less -- Jerry A. Fodor