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Fix getting polar axes in plt.polar() #10674

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Fix getting polar axes in plt.polar() #10674

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671100f
Improve getting of polar axes in plt.polar()
dstansby Mar 5, 2018
b519966
Add newlines to gca() warning
dstansby Mar 5, 2018
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11 changes: 6 additions & 5 deletions lib/matplotlib/figure.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1822,11 +1822,12 @@ def gca(self, **kwargs):
"3.0",
"Calling `gca()` using the same arguments as a "
"previous axes currently reuses the earlier "
"instance. In a future version, a new instance will "
"always be created and returned. Meanwhile, this "
"warning can be suppressed, and the future behavior "
"ensured, by passing a unique label to each axes "
"instance.")
"instance.\n"
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Also added some newlines here to make the warning more readable.

"In a future version, a new instance will "
"always be created and returned.\n"
"Meanwhile, this warning can be suppressed, and the "
"future behavior ensured, by passing a unique label "
"to each axes instance.")
return cax
else:
warnings.warn('Requested projection is different from '
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7 changes: 5 additions & 2 deletions lib/matplotlib/pyplot.py
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Expand Up @@ -2283,12 +2283,15 @@ def polar(*args, **kwargs):
strings, as in :func:`~matplotlib.pyplot.plot`.

"""
# If an axis already exists, check if it has a polar projection
# If an axes already exists, check if it has a polar projection
if gcf().get_axes():
if not isinstance(gca(), PolarAxes):
warnings.warn('Trying to create polar plot on an axis that does '
'not have a polar projection.')
ax = gca(polar=True)
ax = gca()
else:
ax = gcf().add_subplot(1, 1, 1, polar=True)
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umm, I'm not too up on the pyplot interface, but is gca() necessarilly a subplot(111)?

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No, but: If there are axes, use the gca(). If not, make a new one equivalent to subplot(111).

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OK, but I don't get the point of this PR then. Why is this better than whats there now? Is the idea to let plt.polar write on an existing polar axes, despite the fact gca will create a new axes in the future? That doesn't seem right. Sorry if I'm being dense...

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The whole gcasituation is incredibly confusing. I can't make sense of the current behavior and docstrings, and the warning about future behavior makes no sense to me either. gca means "get current axes"; it should not mean "always get a new axes". I think that the coming change to subplot is being incorrectly applied to gca.

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The change was made in #10660 - I think gca should just get the current axis, and not create a new one, and that change should be reverted. ping @anntzer

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I agree that the warning in #10660 is wrong. I need to rethink about the correct way to ultimately get rid of the axes collision behavior.

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Great, I'll close this then.


ret = ax.plot(*args, **kwargs)
return ret

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