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GD::Graph Help

by sunadmn (Curate)
on Aug 29, 2003 at 15:14 UTC ( #287698=perlquestion: print w/replies, xml ) Need Help??

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

Good day monks I have been working with doing a bandwidth test that prints out html for a few days now and with the help of a fellow monk I was able to get a working test to run, but I am now wanting to get the thing to use GD::Graph to make a pretty image..
I have read the perldoc on GD::Graph and think I have it right but I am getting this error "can't call method "plot" on an undefined value". Now from what I can see there should be no issue, but I must be missing something. Below is my code for you to look over and let me know if I am just missing something.
#!/usr/bin/perl -w use warnings; use strict; use Time::HiRes qw ( gettimeofday ) ; use CGI qw(:standard); use GD::Graph::hbars; use CGI::Carp (fatalsToBrowser); my $data = "E"x1020; #start with using 1k blocks shall we? my %cgi_vars; foreach my $pair ( split ( "&", $ENV{'QUERY_STRING'} ) ) { my ( $var, $val ) = split ("=", $pair); $cgi_vars{$var} = $val; } #cgi headers: print "content-type: text/html\n\n"; #take time my ( $start_seconds, $start_microseconds ) = gettimeofday; print "Start Seconds:$start_seconds Start MicroSeconds:$start_microsec +onds<BR/>\n"; #print stuff to thingy if ( $cgi_vars{"data_size"} ) { for ( my $count=0; $count < $cgi_vars{"data_size"}; $count++ ) { print "<!",$data,"->\n"; } } #take time my ( $end_seconds, $end_microseconds ) = gettimeofday; print "End Seconds:$end_seconds End MicroSeconds:$end_microseconds< +BR/>\n"; #compare my $time_delta = ($end_seconds - $start_seconds) + ( ( $end_microsecon +ds - $start_microseconds) / 1000000); if ( $cgi_vars{"data_size"} ) { print "your data transfer of ", $cgi_vars{"data_size"}, "k took ", $ +time_delta, " seconds<BR/>\n"; print "your bandwidth is ",$cgi_vars{"data_size"} / $time_delta ," k +ilobytes/sec<BR/>\n"; my @data = "$time_delta"; my $graph = GD::Graph::hbars->new(400, 300); $graph->set( x_label => 'Transfer Data', y_label => 'Some Label', title => 'Adelphia Speed Test' ); my $gd = my $my_graph->plot(\@data); open(IMG, '>../htdocs/graph.png') or die $!; binmode IMG; print IMG $gd->png; close IMG; } else { print "please invoke as $ENV{'SCRIPT_NAME'}?data_size=100<BR/> \n"; } exit;
Thanks in advanced for all your help!! -Stephen

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Re: GD::Graph Help
by tcf22 (Priest) on Aug 29, 2003 at 15:28 UTC
    You need to call the plot method from the GD::Graph object.

    my $gd = my $my_graph->plot(\@data);
    my $gd = $graph->plot(\@data);
      Great that did seem to work, well atleast I am not getting errors now, but I am alos not seeing the graph on the html page or am I seeing the file graph.png in the ../htdocs dir. Any idea of what else I am missing?? -Thanks
        Try checking to see if the GD::Image object was created.
        my $gd = $graph->plot(\@data) or die $graph->error;

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