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Commit 703b574

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timhoffmQuLogic
timhoffm
and
QuLogic
committed
Cleanup logic and documentation of tripcolor
This issues more and more precise warnings on usage errors but does not change behavior. Co-authored-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
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‎lib/matplotlib/tests/test_triangulation.py

Copy file name to clipboardExpand all lines: lib/matplotlib/tests/test_triangulation.py
+92-34Lines changed: 92 additions & 34 deletions
Original file line numberDiff line numberDiff line change
@@ -12,50 +12,65 @@
1212
from matplotlib.testing.decorators import image_comparison, check_figures_equal
1313

1414

15-
x = [-1, 0, 1, 0]
16-
y = [0, -1, 0, 1]
17-
triangles = [[0, 1, 2], [0, 2, 3]]
18-
mask = [False, True]
19-
20-
21-
@pytest.mark.parametrize('args, kwargs, expected', [
22-
([x, y], {}, [x, y, None, None]),
23-
([x, y, triangles], {}, [x, y, triangles, None]),
24-
([x, y], dict(triangles=triangles), [x, y, triangles, None]),
25-
([x, y], dict(mask=mask), [x, y, None, mask]),
26-
([x, y, triangles], dict(mask=mask), [x, y, triangles, mask]),
27-
([x, y], dict(triangles=triangles, mask=mask), [x, y, triangles, mask]),
28-
])
29-
def test_extract_triangulation_params(args, kwargs, expected):
30-
other_args = [1, 2]
31-
other_kwargs = {'a': 3, 'b': '4'}
32-
x_, y_, triangles_, mask_, args_, kwargs_ = \
33-
mtri.Triangulation._extract_triangulation_params(
34-
args + other_args, {**kwargs, **other_kwargs})
35-
x, y, triangles, mask = expected
36-
assert x_ is x
37-
assert y_ is y
38-
assert_array_equal(triangles_, triangles)
39-
assert mask_ is mask
40-
assert args_ == other_args
41-
assert kwargs_ == other_kwargs
15+
class TestTriangulationParams:
16+
x = [-1, 0, 1, 0]
17+
y = [0, -1, 0, 1]
18+
triangles = [[0, 1, 2], [0, 2, 3]]
19+
mask = [False, True]
20+
21+
@pytest.mark.parametrize('args, kwargs, expected', [
22+
([x, y], {}, [x, y, None, None]),
23+
([x, y, triangles], {}, [x, y, triangles, None]),
24+
([x, y], dict(triangles=triangles), [x, y, triangles, None]),
25+
([x, y], dict(mask=mask), [x, y, None, mask]),
26+
([x, y, triangles], dict(mask=mask), [x, y, triangles, mask]),
27+
([x, y], dict(triangles=triangles, mask=mask), [x, y, triangles, mask])
28+
])
29+
def test_extract_triangulation_params(self, args, kwargs, expected):
30+
other_args = [1, 2]
31+
other_kwargs = {'a': 3, 'b': '4'}
32+
x_, y_, triangles_, mask_, args_, kwargs_ = \
33+
mtri.Triangulation._extract_triangulation_params(
34+
args + other_args, {**kwargs, **other_kwargs})
35+
x, y, triangles, mask = expected
36+
assert x_ is x
37+
assert y_ is y
38+
assert_array_equal(triangles_, triangles)
39+
assert mask_ is mask
40+
assert args_ == other_args
41+
assert kwargs_ == other_kwargs
4242

4343

4444
def test_extract_triangulation_positional_mask():
45-
global x, y, triangles, mask
4645
# mask cannot be passed positionally
46+
mask = [True]
47+
args = [[0, 2, 1], [0, 0, 1], [[0, 1, 2]], mask]
4748
x_, y_, triangles_, mask_, args_, kwargs_ = \
48-
mtri.Triangulation._extract_triangulation_params(x, y, triangles, mask)
49+
mtri.Triangulation._extract_triangulation_params(args, {})
4950
assert mask_ is None
5051
assert args_ == [mask]
51-
# the positional mask has to be catched downstream because this must pass
52+
# the positional mask must be caught downstream because this must pass
5253
# unknown args through
5354

5455

55-
del x
56-
del y
57-
del triangles
58-
del mask
56+
def test_triangulation_init():
57+
x = [-1, 0, 1, 0]
58+
y = [0, -1, 0, 1]
59+
with pytest.raises(ValueError, match="x and y must be equal-length"):
60+
mtri.Triangulation(x, [1, 2])
61+
with pytest.raises(
62+
ValueError,
63+
match=r"triangles must be a \(N, 3\) int array, but found shape "
64+
r"\(3,\)"):
65+
mtri.Triangulation(x, y, [0, 1, 2])
66+
with pytest.raises(
67+
ValueError,
68+
match=r"triangles must be a \(N, 3\) int array, not 'other'"):
69+
mtri.Triangulation(x, y, 'other')
70+
with pytest.raises(ValueError, match="found value 99"):
71+
mtri.Triangulation(x, y, [[0, 1, 99]])
72+
with pytest.raises(ValueError, match="found value -1"):
73+
mtri.Triangulation(x, y, [[0, 1, -1]])
5974

6075

6176
def test_delaunay():
@@ -223,6 +238,49 @@ def test_tripcolor():
223238
plt.title('facecolors')
224239

225240

241+
def test_tripcolor_color():
242+
x = [-1, 0, 1, 0]
243+
y = [0, -1, 0, 1]
244+
fig, ax = plt.subplots()
245+
with pytest.raises(ValueError, match="Missing color parameter"):
246+
ax.tripcolor(x, y)
247+
with pytest.raises(ValueError, match="The length of C must match either"):
248+
ax.tripcolor(x, y, [1, 2, 3])
249+
with pytest.raises(ValueError,
250+
match="length of facecolors must match .* triangles"):
251+
ax.tripcolor(x, y, facecolors=[1, 2, 3, 4])
252+
with pytest.raises(ValueError,
253+
match="'gouraud' .* at the points.* not at the faces"):
254+
ax.tripcolor(x, y, facecolors=[1, 2], shading='gouraud')
255+
with pytest.raises(ValueError,
256+
match="'gouraud' .* at the points.* not at the faces"):
257+
ax.tripcolor(x, y, [1, 2], shading='gouraud') # faces
258+
with pytest.raises(ValueError,
259+
match=r"pass C positionally or facecolors via keyword"):
260+
ax.tripcolor(x, y, C=[1, 2, 3, 4])
261+
262+
# smoke test for valid color specifications (via C or facecolors)
263+
ax.tripcolor(x, y, [1, 2, 3, 4]) # edges
264+
ax.tripcolor(x, y, [1, 2, 3, 4], shading='gouraud') # edges
265+
ax.tripcolor(x, y, [1, 2]) # faces
266+
ax.tripcolor(x, y, facecolors=[1, 2]) # faces
267+
268+
269+
def test_tripcolor_warnings():
270+
x = [-1, 0, 1, 0]
271+
y = [0, -1, 0, 1]
272+
C = [0.4, 0.5]
273+
fig, ax = plt.subplots()
274+
# additional parameters
275+
with pytest.warns(UserWarning, match="Additional positional parameters"):
276+
ax.tripcolor(x, y, C, 'unused_positional')
277+
# facecolors takes precednced over C
278+
with pytest.warns(UserWarning, match="Positional parameter C .*no effect"):
279+
ax.tripcolor(x, y, C, facecolors=C)
280+
with pytest.warns(UserWarning, match="Positional parameter C .*no effect"):
281+
ax.tripcolor(x, y, 'interpreted as C', facecolors=C)
282+
283+
226284
def test_no_modify():
227285
# Test that Triangulation does not modify triangles array passed to it.
228286
triangles = np.array([[3, 2, 0], [3, 1, 0]], dtype=np.int32)

‎lib/matplotlib/tri/triangulation.py

Copy file name to clipboardExpand all lines: lib/matplotlib/tri/triangulation.py
+19-5Lines changed: 19 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -43,7 +43,9 @@ def __init__(self, x, y, triangles=None, mask=None):
4343
self.x = np.asarray(x, dtype=np.float64)
4444
self.y = np.asarray(y, dtype=np.float64)
4545
if self.x.shape != self.y.shape or self.x.ndim != 1:
46-
raise ValueError("x and y must be equal-length 1D arrays")
46+
raise ValueError("x and y must be equal-length 1D arrays, but "
47+
f"found shapes {self.x.shape!r} and "
48+
f"{self.y.shape!r}")
4749

4850
self.mask = None
4951
self._edges = None
@@ -58,13 +60,25 @@ def __init__(self, x, y, triangles=None, mask=None):
5860
else:
5961
# Triangulation specified. Copy, since we may correct triangle
6062
# orientation.
61-
self.triangles = np.array(triangles, dtype=np.int32, order='C')
63+
try:
64+
self.triangles = np.array(triangles, dtype=np.int32, order='C')
65+
except ValueError as e:
66+
raise ValueError('triangles must be a (N, 3) int array, not '
67+
f'{triangles!r}') from e
6268
if self.triangles.ndim != 2 or self.triangles.shape[1] != 3:
63-
raise ValueError('triangles must be a (?, 3) array')
69+
raise ValueError(
70+
'triangles must be a (N, 3) int array, but found shape '
71+
f'{self.triangles.shape!r}')
6472
if self.triangles.max() >= len(self.x):
65-
raise ValueError('triangles max element is out of bounds')
73+
raise ValueError(
74+
'triangles are indices into the points and must be in the '
75+
f'range 0 <= i < {len(self.x)} but found value '
76+
f'{self.triangles.max()}')
6677
if self.triangles.min() < 0:
67-
raise ValueError('triangles min element is out of bounds')
78+
raise ValueError(
79+
'triangles are indices into the points and must be in the '
80+
f'range 0 <= i < {len(self.x)} but found value '
81+
f'{self.triangles.min()}')
6882

6983
if mask is not None:
7084
self.mask = np.asarray(mask, dtype=bool)

‎lib/matplotlib/tri/tripcolor.py

Copy file name to clipboardExpand all lines: lib/matplotlib/tri/tripcolor.py
+72-52Lines changed: 72 additions & 52 deletions
Original file line numberDiff line numberDiff line change
@@ -21,62 +21,82 @@ def tripcolor(ax, *args, alpha=1.0, norm=None, cmap=None, vmin=None,
2121
optionally the *triangles* and a *mask*. See `.Triangulation` for an
2222
explanation of these parameters.
2323
24+
If neither of *triangulation* or *triangles* are given, the triangulation
25+
is calculated on the fly. In this case, it does not make sense to provide
26+
colors at the triangle faces via *C* or *facecolors* because there are
27+
multiple possible triangulations for a group of points and you don't know
28+
which triangles will be constructed.
29+
2430
Parameters
2531
----------
2632
triangulation : `.Triangulation`
2733
An already created triangular grid.
2834
x, y, triangles, mask
29-
Parameters specifying defining the triangular grid. See
30-
`.Triangulation`.
31-
32-
33-
The next argument must be *C*, the array of color values, either
34-
one per point in the triangulation if color values are defined at
35-
points, or one per triangle in the triangulation if color values
36-
are defined at triangles. If there are the same number of points
37-
and triangles in the triangulation it is assumed that color
38-
values are defined at points; to force the use of color values at
39-
triangles use the kwarg ``facecolors=C`` instead of just ``C``.
40-
41-
*shading* may be 'flat' (the default) or 'gouraud'. If *shading*
42-
is 'flat' and C values are defined at points, the color values
43-
used for each triangle are from the mean C of the triangle's
44-
three points. If *shading* is 'gouraud' then color values must be
45-
defined at points.
46-
47-
48-
49-
tripcolor(x, y, [triangles], C, [mask=mask], ...)
50-
51-
52-
The remaining kwargs are the same as for `~.Axes.pcolor`.
35+
Parameters defining the triangular grid. See `.Triangulation`.
36+
This is mutually exclusive with specifying *triangulation*.
37+
C : array-like
38+
The color values, either for the points or for the triangles. Which one
39+
is automatically inferred from the length of *C*, i.e. does it match
40+
the number of points or the number of triangles. If there are the same
41+
number of points and triangles in the triangulation it is assumed that
42+
color values are defined at points; to force the use of color values at
43+
triangles use the keyword argument ``facecolors=C`` instead of just
44+
``C``.
45+
This parameter is position-only.
46+
facecolors : array-like, optional
47+
Can be used alternatively to *C* to specify colors at the triangle
48+
faces. This parameter takes precedence over *C*.
49+
shading : {'flat', 'gouraud'}, default: 'flat'
50+
If 'flat' and the color values *C* are defined at points, the color
51+
values used for each triangle are from the mean C of the triangle's
52+
three points. If *shading* is 'gouraud' then color values must be
53+
defined at points.
54+
other_parameters
55+
All other parameters are the same as for `~.Axes.pcolor`.
56+
57+
Notes
58+
-----
59+
It is possible to pass the triangles positionally, i.e.
60+
``tripcolor(x, y, triangles, C, ...)``. However, this is discouraged.
61+
For more clarity, pass *triangles* via keyword argument.
5362
"""
5463
_api.check_in_list(['flat', 'gouraud'], shading=shading)
5564

5665
tri, args, kwargs = Triangulation.get_from_args_and_kwargs(*args, **kwargs)
5766

58-
# C is the colors array defined at either points or faces (i.e. triangles).
59-
# If facecolors is None, C are defined at points.
60-
# If facecolors is not None, C are defined at faces.
67+
# Parse the color to be in one of (the other variable will be None):
68+
# - facecolors: if specified at the triangle faces
69+
# - point_colors: if specified at the points
6170
if facecolors is not None:
62-
C = facecolors
71+
if args:
72+
_api.warn_external(
73+
"Positional parameter C has no effect when the keyword "
74+
"facecolors is given")
75+
point_colors = None
76+
if len(facecolors) != len(tri.triangles):
77+
raise ValueError("The length of facecolors must match the number "
78+
"of triangles")
6379
else:
80+
# Color from positional parameter C
81+
if not args:
82+
raise ValueError(
83+
"Missing color parameter. Please pass C positionally or "
84+
"facecolors via keyword")
85+
elif len(args) > 1:
86+
_api.warn_external(
87+
"Additional positional parameters {args[1:]!r} are ignored")
6488
C = np.asarray(args[0])
65-
66-
# If there are a different number of points and triangles in the
67-
# triangulation, can omit facecolors kwarg as it is obvious from
68-
# length of C whether it refers to points or faces.
69-
# Do not do this for gouraud shading.
70-
if (facecolors is None and len(C) == len(tri.triangles) and
71-
len(C) != len(tri.x) and shading != 'gouraud'):
72-
facecolors = C
73-
74-
# Check length of C is OK.
75-
if ((facecolors is None and len(C) != len(tri.x)) or
76-
(facecolors is not None and len(C) != len(tri.triangles))):
77-
raise ValueError('Length of color values array must be the same '
78-
'as either the number of triangulation points '
79-
'or triangles')
89+
if len(C) == len(tri.x):
90+
# having this before the len(tri.triangles) comparison gives
91+
# precedence to nodes if there are as many nodes as triangles
92+
point_colors = C
93+
facecolors = None
94+
elif len(C) == len(tri.triangles):
95+
point_colors = None
96+
facecolors = C
97+
else:
98+
raise ValueError('The length of C must match either the number '
99+
'of points or the number of triangles')
80100

81101
# Handling of linewidths, shading, edgecolors and antialiased as
82102
# in Axes.pcolor
@@ -97,13 +117,11 @@ def tripcolor(ax, *args, alpha=1.0, norm=None, cmap=None, vmin=None,
97117

98118
if shading == 'gouraud':
99119
if facecolors is not None:
100-
raise ValueError('Gouraud shading does not support the use '
101-
'of facecolors kwarg')
102-
if len(C) != len(tri.x):
103-
raise ValueError('For gouraud shading, the length of color '
104-
'values array must be the same as the '
105-
'number of triangulation points')
120+
raise ValueError(
121+
"shading='gouraud' can only be used when the colors "
122+
"are specified at the points, not at the faces.")
106123
collection = TriMesh(tri, **kwargs)
124+
colors = point_colors
107125
else:
108126
# Vertices of triangles.
109127
maskedTris = tri.get_masked_triangles()
@@ -112,15 +130,17 @@ def tripcolor(ax, *args, alpha=1.0, norm=None, cmap=None, vmin=None,
112130
# Color values.
113131
if facecolors is None:
114132
# One color per triangle, the mean of the 3 vertex color values.
115-
C = C[maskedTris].mean(axis=1)
133+
colors = point_colors[maskedTris].mean(axis=1)
116134
elif tri.mask is not None:
117135
# Remove color values of masked triangles.
118-
C = C[~tri.mask]
136+
colors = facecolors[~tri.mask]
137+
else:
138+
colors = facecolors
119139

120140
collection = PolyCollection(verts, **kwargs)
121141

122142
collection.set_alpha(alpha)
123-
collection.set_array(C)
143+
collection.set_array(colors)
124144
_api.check_isinstance((Normalize, None), norm=norm)
125145
collection.set_cmap(cmap)
126146
collection.set_norm(norm)

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