FIX: fix colorbars with no scales by jklymak · Pull Request #20327 · matplotlib/matplotlib · GitHub
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FIX: fix colorbars with no scales #20327

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Merged
anntzer merged 1 commit into from
Jun 10, 2021
Merged

FIX: fix colorbars with no scales #20327

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36 changes: 23 additions & 13 deletions lib/matplotlib/colorbar.py
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12 changes: 11 additions & 1 deletion lib/matplotlib/colors.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1152,7 +1152,7 @@ def __init__(self, vmin=None, vmax=None, clip=False):
self.vmin = _sanitize_extrema(vmin)
self.vmax = _sanitize_extrema(vmax)
self.clip = clip
self._scale = scale.LinearScale(axis=None)
self._scale = None # will default to LinearScale for colorbar

@jklymak jklymak May 29, 2021

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Note downstream libraries will likely derive from Normalize, so scale should be None so their norm gets used...

@jklymak jklymak May 30, 2021

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@dstansby can you see if this version works?

@dstansby dstansby May 31, 2021

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Yep, seems to work well with this version.

@jklymak jklymak Jun 1, 2021

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Any chance of a formal review?


@staticmethod
def process_value(value):
Expand Down Expand Up @@ -1334,6 +1334,16 @@ def __call__(self, value, clip=None):
result = np.atleast_1d(result)[0]
return result

def inverse(self, value):
if not self.scaled():
raise ValueError("Not invertible until both vmin and vmax are set")
(vmin,), _ = self.process_value(self.vmin)
(vmax,), _ = self.process_value(self.vmax)
(vcenter,), _ = self.process_value(self.vcenter)

result = np.interp(value, [0, 0.5, 1.], [vmin, vcenter, vmax])
return result


class CenteredNorm(Normalize):
def __init__(self, vcenter=0, halfrange=None, clip=False):
Expand Down
Binary file added lib/matplotlib/tests/baseline_images/test_colorbar/colorbar_twoslope.png
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14 changes: 14 additions & 0 deletions lib/matplotlib/tests/test_colorbar.py
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Original file line number Diff line number Diff line change
Expand Up @@ -771,3 +771,17 @@ def test_inset_colorbar_layout():
np.testing.assert_allclose(cb.ax.get_position().bounds,
[0.87, 0.342, 0.0237, 0.315], atol=0.01)
assert cb.ax.outer_ax in ax.child_axes


@image_comparison(['colorbar_twoslope.png'], remove_text=True,
style='mpl20')
def test_twoslope_colorbar():
# Note that the first tick = 20, and should be in the middle

@greglucas greglucas May 31, 2021

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Adding the ticklabels to the image would be helpful here.

@jklymak jklymak May 31, 2021

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Yeah, I agree, but we really try to avoid labels, because they cause image comparison problems when the font library changes...

# of the colorbar (white)
fig, ax = plt.subplots()

norm = mcolors.TwoSlopeNorm(20, 0, 100)
pc = ax.pcolormesh(np.arange(1, 11), np.arange(1, 11),
np.arange(100).reshape(10, 10),
norm=norm, cmap='RdBu_r')
fig.colorbar(pc)
3 changes: 1 addition & 2 deletions lib/matplotlib/tests/test_colors.py
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