With Gruff 0.2.8 a spider graph is not correctly scaled and draws a keyword at the bottom of the graph outside the image.
This is a regression from previous versions of gruff, which drew this graph correctly. The following code shows the
problem:

require 'gruff'

g = Gruff::Spider.new(4, '350x300')

1.upto(12) do |i|
  g.data("Keyword #{i}", [(i/4).floor])
end

g.write('test-image.png')

Date: 2007-03-08 09:47
Sender: Hans de Graaff

I've added a simple patch which at least fixes the symptom
by taking a bit less space for the graph. It seems to me
that the diameter calculation doesn't take the offset into
account.

A better fix would be to take string length into account
when drawing the labels (e.g. only 20px for top and bottom
labels and more for the left and right labels, but my head
hurt when quickly thinking about the path involved. :-)