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Merged
merged 5 commits into from
Aug 8, 2022
Merged

warning when scatter plot color settings discarded #23516

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cf325c2
Warning when scatter plot color settings discarded
swaltek Jul 29, 2022
67841a9
Update lib/matplotlib/axes/_axes.py
swaltek Aug 5, 2022
30474eb
Wrapped 23516-MS.rst lines at 80 characters
swaltek Aug 5, 2022
ca0b9ea
Fixed tests to look for proper warning message
swaltek Aug 5, 2022
586a1a5
Update doc/api/next_api_changes/behavior/23516-MS.rst
swaltek Aug 7, 2022
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6 changes: 6 additions & 0 deletions doc/api/next_api_changes/behavior/23516-MS.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
Warning when scatter plot color settings discarded
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When making an animation of a scatter plot, if you don't set *c* (the color
value parameter) when initializing the artist, the color settings are ignored.
`.Axes.scatter` now raises a warning if color-related settings are changed
without setting *c*.
10 changes: 10 additions & 0 deletions lib/matplotlib/axes/_axes.py
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Expand Up @@ -4559,6 +4559,16 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
collection.set_cmap(cmap)
collection.set_norm(norm)
collection._scale_norm(norm, vmin, vmax)
else:
extra_kwargs = {
'cmap': cmap, 'norm': norm, 'vmin': vmin, 'vmax': vmax
}
extra_keys = [k for k, v in extra_kwargs.items() if v is not None]
if any(extra_keys):
keys_str = ", ".join(f"'{k}'" for k in extra_keys)
_api.warn_external(
"No data for colormapping provided via 'c'. "
f"Parameters {keys_str} will be ignored")
collection._internal_update(kwargs)

# Classic mode only:
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19 changes: 19 additions & 0 deletions lib/matplotlib/tests/test_axes.py
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Expand Up @@ -2383,6 +2383,25 @@ def test_scatter_color(self):
with pytest.raises(ValueError):
plt.scatter([1, 2, 3], [1, 2, 3], color=[1, 2, 3])

@pytest.mark.parametrize('kwargs',
[
{'cmap': 'gray'},
{'norm': mcolors.Normalize()},
{'vmin': 0},
{'vmax': 0}
])
def test_scatter_color_warning(self, kwargs):
warn_match = "No data for colormapping provided "
# Warn for cases where 'cmap', 'norm', 'vmin', 'vmax'
# kwargs are being overridden
with pytest.warns(Warning, match=warn_match):
plt.scatter([], [], **kwargs)
with pytest.warns(Warning, match=warn_match):
plt.scatter([1, 2], [3, 4], c=[], **kwargs)
# Do not warn for cases where 'c' matches 'x' and 'y'
plt.scatter([], [], c=[], **kwargs)
plt.scatter([1, 2], [3, 4], c=[4, 5], **kwargs)

def test_scatter_unfilled(self):
coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
marker=mmarkers.MarkerStyle('o', fillstyle='none'),
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4 changes: 2 additions & 2 deletions lib/matplotlib/tests/test_colorbar.py
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Expand Up @@ -280,7 +280,7 @@ def test_remove_from_figure(use_gridspec):
Test `remove` with the specified ``use_gridspec`` setting
"""
fig, ax = plt.subplots()
sc = ax.scatter([1, 2], [3, 4], cmap="spring")
sc = ax.scatter([1, 2], [3, 4])
sc.set_array(np.array([5, 6]))
pre_position = ax.get_position()
cb = fig.colorbar(sc, use_gridspec=use_gridspec)
Expand All @@ -296,7 +296,7 @@ def test_remove_from_figure_cl():
Test `remove` with constrained_layout
"""
fig, ax = plt.subplots(constrained_layout=True)
sc = ax.scatter([1, 2], [3, 4], cmap="spring")
sc = ax.scatter([1, 2], [3, 4])
sc.set_array(np.array([5, 6]))
fig.draw_without_rendering()
pre_position = ax.get_position()
Expand Down