Thanks, Paul! A bit of tweaking in my actual app but it now works beautifully!
On 18/01/2011, at 4:08 PM, Paul Ivanov wrote:
> 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:
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