Re: [Matplotlib-users] eps/pdf/svg contourf contours don't overlap properly with high resolution data

[ayuffa <ay...@gm...>]

Yes, it's true that uncommenting path.simplify : False line inside the
matplotlibrc file fixes the artifacts.  However, it also produces HUGE
PDF/EPS file sizes.  Perhaps, it's better to change path.simplify parameter
as needed inside the code via:

import matplotlib.pyplot as plt
plt.rcParams['path.simplify'] = False
# Plotting Code Block goes here
plt.rcdefaults()

Does anyone have another fix for this problem that DOES NOT produce HUGE
PDF/EPS files?


efiring wrote:
> 
> Jouni K. Seppänen wrote:
>> Jordan Dawe <jd...@eo...> writes:
>> 
>>> Contourf plots that I output in vector format files have little
>>> triangular glitches at the contour boundaries if the contoured array
>>> is larger than about 200x200. The same files in png format are
>>> perfect, even at very high dpi values.
>> 
>> The current svn trunk doesn't have the really jarring little triangles
>> (at least in the pdf output), but there are still several very obtuse
>> white triangles between the regions. Rasterization at a high dpi makes
>> the output somewhat better at the cost of larger output files:
>> 
>> c=contourf(X, Y, Z, 10)
>> axis((-3, 3, -3, 3))
>> savefig('unrasterized.pdf')
>> for d in c.collections:
>>     d.set_rasterized(True)
>> savefig('rasterized.pdf',dpi=200)
> 
> 
> At least in the trunk--and maybe in 0.99.0--the problem is caused by 
> path simplification.  In the trunk, for the eps file, it goes away 
> completely if I use a matplotlibrc with
> 
> path.simplify : False
> 
> In the trunk, what seems to be happening is that when a contour boundary 
> is almost straight, but has an inflection point, the curves for the 
> adjacent patch boundaries are simplified slightly differently.  This is 
> not surprising; if nothing else, the path will be traveled in a 
> different direction when it is an outer boundary than when it is an 
> inner boundary (for a set of concentric boundaries).
> 
> Jordan, try using a local matplotlibrc with the above.  Unless you are 
> already customizing via a local matplotlibrc, that line is all you need.
> 
> One reason the trunk behavior differs from 0.99.0 is that contour patch 
> boundaries are now being turned into compound boundaries instead of 
> using a branch cut to connect the outside path to the inside path.  I 
> suspect simplification is causing the artifacts in both cases, though.
> 
> Eric
> 
> 
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