[rrd-users] Problems graphing

[Laura McCord]

I have my data loaded into an array but everytime I try to graph the 
data I get a "Can't call method "png" on an undefined value...

I am using Perl and the Graph module to produce a bar graph. Here is a 
sample of my data and my source code. Perhaps someone will notice what I 
am doing wrong.

Thanks.


Here is some sample data:

Fri Sep 26 00:00:00 2008          0.1
Fri Sep 26 01:00:00 2008          0.0
Fri Sep 26 02:00:00 2008          0.1
Fri Sep 26 03:00:00 2008          0.1
Fri Sep 26 04:00:00 2008          0.2
Fri Sep 26 05:00:00 2008          0.1
Fri Sep 26 06:00:00 2008          0.2
Fri Sep 26 07:00:00 2008          0.1
Fri Sep 26 08:00:00 2008          0.2
Fri Sep 26 09:00:00 2008          0.2
Fri Sep 26 10:00:00 2008          0.2

Here is a snippet of code:
        #Every Hour
       my $res = '60';

       # Start on Sep 1st
       my $start_t = "1220227200";
       my $start_t_res = int($start_t/$res)*$res;

       #End on Today's Date
       my $end_t = "(int($start_t/$res)*$res)";
       my ($start,$step,$names,$data) = 
RRDs::fetch("stats.rrd","AVERAGE","-r","$res","-s", 
"$start_t_res","-e","now");

       print "Start:       ", scalar localtime($start), " ($start)\n";
        print "Step size:   $step seconds\n";
        print "DS names:    ", join (", ", @$names)."\n";
        print "Data points: ", $#$data + 1, "\n";
        print "Data:\n";
        foreach my $line (@$data) {
               $start += $step;
               $min++;
                  #Here I am only loading hourly data into the array
                  if($min == 60){
                        $array1[$i] = localtime($start);
                          foreach my $val (@$line) {
                               $array2[$i] = $val;
                           }
                        $i++;
                        $min=0;
                  }
        }

       for($i=0;$i < @array1; $i++){
               print $array1[$i]." ";
               printf "%12.1f ", $array2[$i];
               print "\n";
       }

       @actualdata = (\@array1,\@array2);

       my $graph = new GD::Graph::bars;
        $graph->set(
           x_label         => 'Date/Time',
           y_label         => 'Messages',
           title           => 'Dropped Messages',
           y_max_value     => 10,
           y_tick_number   => 1,
           y_label_skip    => 1,

           # shadows
           bar_spacing     => 10,
           shadow_depth    => 4,
           shadowclr       => 'dred',

           transparent     => 0,
       ) or warn $graph->error;

       my $image = $graph->plot(\@actualdata)->png();