Tim Burgess, on 2011-01-18 13:32, wrote: > I'm generating images that I want to use as overlays in Google > Earth. Thus, I would like the masked portion of the numpy > arrays I am using to appear as transparent. However, I seem to > consistently get white instead of a transparent point. > > To clarify the issue, I wrote this short piece of code. I am > setting both the figure background to transaprent and the > masked value to transparent but I get white. > > I have pulled the current svn code and built matplotlib. I get > the same issue. > > from numpy import ma > import matplotlib.pyplot as plt > from pylab import colorbar, imshow, show, cm > > > def main(): > a = ma.array([[1,2,3],[4,5,6]],mask=[[0,0,1],[0,0,0]]) > fig = plt.figure() > fig.patch.set_alpha(0.0) > cmap = cm.jet > cmap.set_bad(alpha=0.0) > imshow(a, interpolation='nearest', cmap=cmap) > colorbar() > show()
Hi Tim, sorry to hear of your troubles - add these two lines to get your desired effect: ax = plt.gca() ax.patch.set_alpha(0.0) The figure has a patch associated with it, but so does each axes subplot, which is what you were seeing through the transparent portion of your masked array image. best, -- Paul Ivanov 314 address only used for lists, off-list direct email at: http://pirsquared.org | GPG/PGP key id: 0x0F3E28F7
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