GD::Graph labeling

[chinman]

Hey, I'm in need of some Monk wisdom. I've been dorking around with GD::Graph to try to plot an x,y line graph with lots o' points (>1000). I've got the basics working fine. Well, I'd like to label the maxima, or maybe the 10 biggest y values by using the show_values option. The problem is if I turn labeling on with my "thousand points of light" I've got way too many data point labels and everything runs together. I'm wondering if anyone knows a way to label just a few without blowing away the rest of the points. I've tried using the $data->copy method, followed by setting values to undefined but that does not appear to do what I want. It seems like when you say show_values it always wants to show_values for all data points. Thanks in advance for the help!

[Prof Avery]

Try using values_format, formatting the maxima as numbers and everything else as an empty string, e.g.

sub v_format {
  my $value = shift;

  if ($value >= ($MAX - $EPSILON)) {
    return $value
  } else {
    return '';
}

$my_graph->set('values_format' => \&v_format);

[chinman]

Prof Avery,

Thanks, that was a huge help! Somehow, values_format did not come up on my radar screen.

Regards,

chinman

[ryddler]

If I'm reading your post correctly, take a look at these values in the docs for GD::Graph

x_label_skip, y_label_skip

Print every x_label_skipth number under the tick on the
x axis, and every y_label_skipth number next to the tick
on the y axis. Default: 1 for both.

Update:
I misread this question, but the settings I pointed out above are still useful for some graphing ops, so I'll leave the post intact.

ryddler

[chinman]

ryddler, Thanks for your post. Yeah, what I'm looking to do is label certain points on the graph (like the maximum Y values). I've got the tic labeling figured out. While I'm on this topic...are there any monk recommendations for another graphing module that do a better job at what I'm trying to do? Basically, I'm taking spectra which contain thousands of x, y data points and I just want to do some automated labeling of some of the biggest peaks. Thanks... chinman