GDGraph charts

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

I am trying to plot a simple line graph on a web page using the GDGraph module. So far all i seem to get after i ran my script is an empty image My code is as follows:

#!/usr/local/bin/perl5

use GD::Graph;
use GD::Graph::lines;
use CGI;
my $query = new CGI;

 @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 $format;

    print "Content-type: image/png\n\n";
    
    # create a new graph
    my $graph =  GD::Graph::lines->new(400,400);
        
    $graph->set( x_label           => 'X Label',
          y_label           => 'Y label',
          title             => 'Some simple graph',
         );
    
    $format = $graph->export_format;
    
    print $query->header("image/$format");
    
    binmode STDOUT;

   #(the parentheses after $format are necessary, to help the compiler
+ decide that 
   # you mean a method name here) 
   print $graph->plot(\@data)->$format();
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Re: GDGraph charts by btrott (Parson) on Jul 17, 2000 at 22:59 UTC
I'm not sure of your exact error, here, because it's very hard to see what's in the @data array (use <code> tags!). But you're printing out the header twice... did you see that? First you print it out by hand, then you print it out using CGI::header. Take one of those out. Also check to see that @data has what you think it should.	[reply]
(chromatic) Re: GDGraph charts by chromatic (Archbishop) on Jul 18, 2000 at 02:46 UTC
Apologies if this is an incredibly stupid comment, but my documentation suggests a slightly different approach: `my $image = $graph->plot(\@data); print $image->png;` [download] (Code taken from the 2nd edition of Programming CGI with Perl.)	[reply] [d/l]