Alpha values not preserved with Ellipse and PatchCollection

Hello,

The following code should produce identical plots, but in the second case the alpha value is ignored:

···

---

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as mpl
from matplotlib.patches import Ellipse
from matplotlib.collections import PatchCollection

fig = mpl.figure()
ax = fig.add_subplot(111)
ax.add_patch(Ellipse((0.5,0.5),0.7,0.3,angle=30,alpha=0.3))
fig.savefig('test1.png')

fig = mpl.figure()
ax = fig.add_subplot(111)
ax.add_collection(PatchCollection([Ellipse((0.5,0.5),0.7,0.3,angle=30,alpha=0.3)],match_original=True))
fig.savefig('test2.png

---

Is this a bug? I'm using the latest svn version of matplotlib.

Thanks,

Thomas

Thomas Robitaille wrote:

Hello,

The following code should produce identical plots, but in the second case the alpha value is ignored:

---

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as mpl
from matplotlib.patches import Ellipse
from matplotlib.collections import PatchCollection

fig = mpl.figure()
ax = fig.add_subplot(111)
ax.add_patch(Ellipse((0.5,0.5),0.7,0.3,angle=30,alpha=0.3))
fig.savefig('test1.png')

fig = mpl.figure()
ax = fig.add_subplot(111)
ax.add_collection(PatchCollection([Ellipse((0.5,0.5), 0.7,0.3,angle=30,alpha=0.3)],match_original=True))
fig.savefig('test2.png

---

Is this a bug? I'm using the latest svn version of matplotlib.

Yes. Alpha-handling in general is a confusing mess in mpl. Ideally, it needs an overhaul rather than an isolated bug-fix or two. This might best be done in the context of a color-handling overhaul, which we have discussed a little bit.

Eric

···

Thanks,

Thomas

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