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[NF] Add 'truncate' and 'join' methods to colormaps. #7716

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[NF] Add 'truncate' and 'join' methods to colormaps. #7716

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ea42661
NF - Add 'truncate' and 'join' methods to colormaps.
lkilcher Dec 31, 2016
e15203a
Some pep8 fixes.
lkilcher Dec 31, 2016
42bdcb0
Update .join docstring to include the parameter.
lkilcher Dec 31, 2016
60ebf94
Move methods to `Colorbar`.
lkilcher Jan 1, 2017
f06bf46
Add the __add__ method, and doc.
lkilcher Jan 1, 2017
81ddd1c
Add a `name` parameter to `truncate`
lkilcher Jan 1, 2017
71742d7
Refactor onto a 'join_colormaps' function
lkilcher Jan 1, 2017
fa9f56a
Some ideas for a colormap __getitem__ method.
lkilcher Jan 1, 2017
aba18e0
Fix some floating-point arithmetic issues for low-N.
lkilcher Jan 18, 2017
652b4cf
Simplify getitem.
lkilcher Feb 1, 2017
c2bd712
Add more tests.
lkilcher Feb 1, 2017
6f0a342
pep8
lkilcher Feb 2, 2017
9de0239
Add whats_new and update docstring
lkilcher Sep 27, 2017
48172c7
Compare cmap values in tests (not image comparisons)
lkilcher May 18, 2018
8592695
pep8 fixes
lkilcher May 18, 2018
17e576e
Increase coverage.
lkilcher May 19, 2018
9caba24
Test: 100% coverage!
lkilcher May 20, 2018
2384d0b
Merge branch 'master' into colormap_utils
lkilcher Aug 13, 2018
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Increase coverage.
  • Loading branch information
@lkilcher
lkilcher committed May 19, 2018
commit 17e576e97ea1db3815c0e8a7aa378ad2a5c8812d
4 changes: 3 additions & 1 deletion lib/matplotlib/colors.py
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Original file line number Diff line number Diff line change
Expand Up @@ -833,7 +833,7 @@ def __getitem__(self, item):
sss[1] += 1
if sss[2] is None:
sss[2] = self.N * 1j * (sss[1] - sss[0])
else:
elif all([s is None or abs(s) > 1 for s in sss[:2]]):
# This is an integer-style itemization
if sss[0] is None:
sss[0] = 0
Expand All @@ -852,6 +852,8 @@ def __getitem__(self, item):
if sss[0] < 0 or sss[0] >= 1 or sss[1] <= 0 or sss[1] > 1:
raise IndexError("Invalid colorbar itemization - outside "
"bounds")
else:
raise IndexError("Invalid colorbar itemization")
points = np.mgrid[slice(*sss)]
elif isinstance(item, (list, np.ndarray)):
name = self.name + '[<indexed>]'
Expand Down
79 changes: 74 additions & 5 deletions lib/matplotlib/tests/test_colorbar.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@
from matplotlib import rc_context
from matplotlib.testing.decorators import image_comparison
import matplotlib.pyplot as plt
from matplotlib.colors import BoundaryNorm, LogNorm
from matplotlib.colors import BoundaryNorm, LogNorm, join_colormaps
from matplotlib.cm import get_cmap
from matplotlib.colorbar import ColorbarBase

Expand Down Expand Up @@ -219,11 +219,25 @@ def test_join_colorbar():
)
assert np.allclose(vals, _vals)

# +code-coverage for name kwarg and when fractions is unspecified
cmap = join_colormaps([cmap1, cmap2, cmap1], name='test-map')
vals = cmap(test_points)
_vals = np.array(
[[0.229739, 0.322361, 0.545706, 1., ],
[0.993248, 0.906157, 0.143936, 1., ],
[0.48387097, 1., 0.48387097, 1., ],
[0.267004, 0.004874, 0.329415, 1., ],
[0.369214, 0.788888, 0.382914, 1., ]]
)
assert np.allclose(vals, _vals)


def test_truncate_colorbar():
test_points = [0.1, 0.3, 0.5, 0.7, 0.9]
vir32 = plt.get_cmap('viridis', 32)
vir128 = plt.get_cmap('viridis', 128)

cmap = plt.get_cmap('viridis', 32).truncate(0.2, 0.7)
cmap = vir32.truncate(0.2, 0.7)
vals = cmap(test_points)
_vals = np.array(
[[0.243113, 0.292092, 0.538516, 1.],
Expand All @@ -234,7 +248,20 @@ def test_truncate_colorbar():
)
assert np.allclose(vals, _vals)

cmap = plt.get_cmap('viridis', 128)[0.2:-0.3:16j]
# +code-coverage
cmap = vir32.truncate(0.2, 0.7, name='test-map', N=128)
vals = cmap(test_points)
_vals = np.array(
[[0.243113, 0.292092, 0.538516, 1., ],
[0.182256, 0.426184, 0.55712, 1., ],
[0.144759, 0.519093, 0.556572, 1., ],
[0.119423, 0.611141, 0.538982, 1., ],
[0.180653, 0.701402, 0.488189, 1., ]]
)
assert np.allclose(vals, _vals)

# Use __getitem__ fractional complex slicing
cmap = vir128[0.2:-0.3:16j]
vals = cmap(test_points)
_vals = np.array(
[[0.241237, 0.296485, 0.539709, 1.],
Expand All @@ -245,7 +272,8 @@ def test_truncate_colorbar():
)
assert np.allclose(vals, _vals)

cmap = plt.get_cmap('viridis', 128)[25:90]
# Use __getitem__ fractional integer slicing
cmap = vir128[25:90]
vals = cmap(test_points)
_vals = np.array(
[[0.233603, 0.313828, 0.543914, 1.],
Expand All @@ -256,7 +284,8 @@ def test_truncate_colorbar():
)
assert np.allclose(vals, _vals)

cmap = plt.get_cmap('viridis', 128)[25:90:16j]
# Use __getitem__ integer complex slicing
cmap = vir128[25:90:16j]
vals = cmap(test_points)
_vals = np.array(
[[0.241237, 0.296485, 0.539709, 1.],
Expand All @@ -267,6 +296,46 @@ def test_truncate_colorbar():
)
assert np.allclose(vals, _vals)

# Use __getitem__ discrete slicing
cmap = vir128[[10, 12, 15, 35, 60, 97]]
vals = cmap(test_points)
_vals = np.array(
[[0.283197, 0.11568, 0.436115, 1., ],
[0.282884, 0.13592, 0.453427, 1., ],
[0.21813, 0.347432, 0.550038, 1., ],
[0.13777, 0.537492, 0.554906, 1., ],
[0.395174, 0.797475, 0.367757, 1., ]]
)
assert np.allclose(vals, _vals)


def test_truncate_colorbar_fail():
vir128 = plt.get_cmap('viridis', 128)

with pytest.raises(ValueError, match='less than'):
vir128.truncate(0.7, 0.3)

with pytest.raises(ValueError, match='not a truncation'):
vir128.truncate(0, 1)

with pytest.raises(ValueError, match='interval'):
vir128.truncate(0.3, 1.1)

with pytest.raises(ValueError, match='interval'):
vir128.truncate(-0.1, 0.7)

with pytest.raises(IndexError, match='must contain >1 color'):
vir128[[3]]

with pytest.raises(IndexError, match='Invalid colorbar itemization'):
# Tuple indexing of colorbars not allowed.
vir128[3, 5, 9]

with pytest.raises(IndexError, match='Invalid colorbar itemization'):
# Currently you can't mix-match fractional and int style indexing.
# This could be changed...
vir128[0.3:100]


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Not sure this requires image comparisons (which are repo-heavy). Can you just test on the returned colormaps?

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Hi Jody! I hadn't thought of this, but it makes sense. Are the colormaps sitting somewhere that I can compare to, or... ?

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Hi Levi, I'd just evaluate the colormap at 5 or 6 locations and assert that the values returned are what you say they should be. That seems trivial but if someone mucks with your code they will have to also change the test and thats a good warning to double check what was done.

@image_comparison(baseline_images=['colorbar_single_scatter'],
extensions=['png'], remove_text=True,
Expand Down