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copy a color map object does not isolate changes to cm #8299
Description
Activity
- added this to the milestone on Mar 15, 2017
Exact work:
- implement __copy__ and maybe __deepcopy__ on ColorMap
Tagging as medium because the color map code is a bit convoluted .
I can reproduce this issue with:
import matplotlib.pyplot as plt import copy import numpy as np %matplotlib inline data = np.ma.masked_array([[1,2,3],[2,3,4]], mask=[[1,0,0],[0,0,0]]) cm = plt.cm.Reds plt.imshow(data,cmap=cm) plt.show() cm2 = copy.copy(cm) cm2.set_bad('b') plt.imshow(data,cmap=cm)In the second plot the image contains blue when it should remain white. copy.deepcopy works as expected, though. Would the solution be to have copy call deepcopy?
Implementing __copy__ should be enough to get the desired behavior.
- added a commit that references this issue on Mar 24, 2017
If you do cm2 = copy.copy(cm) and the original color map has been used at least once, then the copy will share a reference to self._lut (which is what is used to __call__ to map from values -> rgba). Any calls to set_over, set_under, or set_bad will be shared by all copies (as they update self._lut in place).