Rich,
The transforms can be modified at drawing time, so you need to get the
pixel locations after the plot has been drawn. Are you doing this?
Eric
Rich Fought wrote:
> Rich Fought wrote:
>> I'm plotting some grid data using pcolor, and trying to get canvas pixel
>> locations of data points using the
>>
>> ax.transData.xy_tup()
>>
>> method. I am saving these figures to PNG files using the default Agg
>> backend. When I open these images up in Gimp and check the pixel
>> locations, the X pixel locations are accurate, but the Y pixel locations
>> I am getting from matplotlib seem to be exaggerated the further away
>> from Y=0 I go. Am I using this method incorrectly? Could this be an
>> artifact of the rendering to PNG?
>>
>
> I determined what is causing the exaggerated y-pixel values. I was using
>
> axes().set_aspect('equal')
>
> on the figure and this apparently does not get taken into account when using
>
> ax.transData.xy_tup()
>
> I tried setting the aspect in the original fig.add_subplot, but got the
> same incorrect results.
>
> ax = fig.add_subplot(111, aspect='equal')
>
> Leaving the aspect alone gives correct pixel results.
>
> Is this a bug, or expected behavior?
>
> Rich
>
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