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Fix huge imshow range #18458

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Merged
merged 2 commits into from
Sep 14, 2020
Merged

Fix huge imshow range #18458

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d13b20a
MNT: do not cache a version of inverse transform that can go stale
tacaswell Sep 11, 2020
b23708a
FIX: special-case LogNorm when resealing
tacaswell Sep 11, 2020
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6 changes: 4 additions & 2 deletions lib/matplotlib/colors.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1251,7 +1251,6 @@ def __init__(self, *args, **kwargs):
**{k: ba.arguments.pop(k) for k in ["vmin", "vmax", "clip"]})
self._scale = scale_cls(axis=None, **ba.arguments)
self._trf = self._scale.get_transform()
self._inv_trf = self._trf.inverted()

def __call__(self, value, clip=None):
value, is_scalar = self.process_value(value)
Expand Down Expand Up @@ -1283,7 +1282,10 @@ def inverse(self, value):
raise ValueError("Invalid vmin or vmax")
rescaled = value * (t_vmax - t_vmin)
rescaled += t_vmin
return self._inv_trf.transform(rescaled).reshape(np.shape(value))
return (self._trf
.inverted()
.transform(rescaled)
.reshape(np.shape(value)))

Norm.__name__ = base_norm_cls.__name__
Norm.__qualname__ = base_norm_cls.__qualname__
Expand Down
8 changes: 6 additions & 2 deletions lib/matplotlib/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -534,9 +534,13 @@ def _make_image(self, A, in_bbox, out_bbox, clip_bbox, magnification=1.0,
resampled_masked = np.ma.masked_array(A_resampled, out_mask)
# we have re-set the vmin/vmax to account for small errors
# that may have moved input values in/out of range
s_vmin, s_vmax = vrange
if isinstance(self.norm, mcolors.LogNorm):
if s_vmin < 0:
s_vmin = max(s_vmin, np.finfo(scaled_dtype).eps)
with cbook._setattr_cm(self.norm,
vmin=vrange[0],
vmax=vrange[1],
vmin=s_vmin,
vmax=s_vmax,
):
output = self.norm(resampled_masked)
else:
Expand Down
19 changes: 19 additions & 0 deletions lib/matplotlib/tests/test_image.py
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Expand Up @@ -1204,3 +1204,22 @@ def test_imshow_quantitynd():
ax.imshow(arr)
# executing the draw should not raise an exception
fig.canvas.draw()


@check_figures_equal(extensions=['png'])
def test_huge_range_log(fig_test, fig_ref):
data = np.full((5, 5), -1, dtype=np.float64)
data[0:2, :] = 1E20

ax = fig_test.subplots()
im = ax.imshow(data, norm=colors.LogNorm(vmin=100, vmax=data.max()),
interpolation='nearest', cmap='viridis')

data = np.full((5, 5), -1, dtype=np.float64)
data[0:2, :] = 1000

cm = copy(plt.get_cmap('viridis'))
cm.set_under('w')
ax = fig_ref.subplots()
im = ax.imshow(data, norm=colors.Normalize(vmin=100, vmax=data.max()),
interpolation='nearest', cmap=cm)