I'm having strange problems with contourf plots. The plotting routine is rather elaborate, so I don't have an easy way to reproduce the problem (unfortunately). The problem should be evident from the attachments. As you can see, the contourf routine doesn't color the whole plot area. Also, after some editing in Adobe Illustrator, it is also easy to see that some contours are drawn on top of others. This must surely be a bug?
I would like to note that this happened on the TkAgg (using show()), Agg (png format), ps (eps format), macosx (using show()) and pdf backends. Also, for some data sets, the plot turns out just fine - I get this problem only for some data sets. I have no idea how to debug this, so I'd appreciate any hints you might provide.
The file original.pdf shows the matplotlib result. The file edited.pdf shows that you have contours on top of each other. The file gnuplot.png gives an idea of what the end result should be: a lot of bumps around 3.5 eV, but some of this structure is missing from the contourf plots. The gnuplot plot was generated from the same data (ASCII text) file.
original.pdf (79.3 KB)
edited.pdf (175 KB)