using GD::graph:lines

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi monks, I'm trying to draw a simple graph with GD::graph::lines and am following the exact instruction on the CPAN web-site. Anyway, The error message i get is Can't call method "plot" on an undefined value at plot_graph.pl line 32. but i really can t see the error or how @data is undefined. If anyone can spot the error i would be very happy indeed. cheers!

#!/biol/programs/perl/bin/perl -w

use GD::Graph::lines;



 @data = (
      ["1st","2nd","3rd","4th","5th","6th","7th", "8th", "9th"],
      [    1,    2,    5,    6,    3,  1.5,    1,     3,     4],
      [ sort { $a <=> $b } (1, 2, 5, 6, 3, 1.5, 1, 3, 4) ]
    );

my $graph = GD::Graph::lines->new(400,400);


$graph->set (

   x_label => 'values1',
   y_label => 'values2',
   title   => 'Correlate',
   )  or die $my_graph->error;


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

open (IMG, '>file.png') or die $!;
binmode IMG;
print IMG $gd->png;
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Re: using GD::graph:lines by zby (Vicar) on Mar 10, 2003 at 10:57 UTC
You seem to change the name from `$graph` to `$my_graph` in the middle of the program. `use strict` would give you a better error description.	[reply] [d/l] [select]
Re: using GD::graph:lines by Hofmator (Curate) on Mar 10, 2003 at 11:54 UTC
As zby pointed out, all occurrences of $my_graph should be replaced by $graph. But you are right about this being straight out of the doc - these examples should work. So drop the module author a line that this inconsistency gets fixed, he'll be happy about it ... -- Hofmator	[reply]