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copied!<p>To clarify: are you declaring the <code>y_max_value</code> height and your data is overflowing that bound? Or is GD::Graph miscalculating the correct upper limit?</p> <p>If you're setting the value, you need to fix your values to that upper bound. GD::Graph is only doing what you're telling it to do. (Which is more or less what Brian said).</p> <p>OTOH, I've found that GD::Graph doesn't always cope well with cumulative (stacked) graphs, and tends to overestimate the <code>y_max_value</code> in those circumstances. It can also produce some unattractive values on the Y axis, with floating point numbers at the tick values. Is this what you're really trying to solve?</p> <p>Having had both these problems, we've found a solution using Tie::RangeHash to create 'tidy' increments that always produce 5 integer tick points.</p> <pre><code>use Tie::RangeHash ; my $y_ranges = new Tie::RangeHash Type => Tie::RangeHash::TYPE_NUMBER; $y_ranges->add(' -500, -101', '-25'); $y_ranges->add(' -100, -26', '-10'); $y_ranges->add(' -25, -1', '-5'); $y_ranges->add(' 0, 25', '5'); $y_ranges->add(' 26, 100', '10'); $y_ranges->add(' 101, 500', '25'); $y_ranges->add(' 501, 1000', '100'); $y_ranges->add(' 1001, 5000', '250'); $y_ranges->add(' 5001, 10000','1000'); $y_ranges->add('10001, 50000','2500'); $y_ranges->add('50001,' ,'5000'); sub set_y_axis { # This routine over-rides the y_max_value calculation in GD::Graph, which produces double the # required limit, and therefore a lot of white-space... return 1 unless @_ ; #no point going any further if no arguments were provided, however result has to be #non-zero to avoid /0 errors in GD::Graph my @a = map { $_ || 0 } @_ ; #array may have undefs in it. Set null to zero for calc of max my ($y_max) = sort { $b <=> $a } @a ; # Get largest total for y-axis my $y_range = $y_ranges->fetch($y_max); my $y_axis = ($y_max%$y_range==0) ? $y_max+$y_range : ($y_max - ($y_max%$y_range) + $y_range); sprintf("%d", $y_axis); } sub my_graph { my @ymax; # generate data... foreach loop etc push(@ymax, $this_y_value); # append y-value or cumulative y-value as appropriate # etc. my $graph = GD::Graph::lines->new(750, 280); $graph->set( y_max_value => set_y_axis(@ymax), x_labels_vertical => 1, transparent => 1, # etc ); # etc } </code></pre> <p>Hope that's useful to you.</p>

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