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Added tripcolor triangle-centred colour values. #850

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Merged
merged 7 commits into from
Aug 16, 2012
Merged

Added tripcolor triangle-centred colour values. #850

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7c7b037
Added tripcolor triangle-centred colour values.
ianthomas23 Apr 22, 2012
b1812f7
tripcolor shading='faceted' deprecated in favour of edgecolors.
ianthomas23 Aug 13, 2012
8a21c57
Removed confusing tripcolor kwarg colorpoints and using facecolors
ianthomas23 Aug 14, 2012
f5f357e
Added tripcolor facecolors example.
ianthomas23 Aug 14, 2012
ece0fb1
Added tripcolor unit test.
ianthomas23 Aug 14, 2012
cd9212d
Corrected tripcolor documentation.
ianthomas23 Aug 16, 2012
4f5d3ce
Replaced backslash line continuators with parentheses.
ianthomas23 Aug 16, 2012
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Added tripcolor triangle-centred colour values.
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@ianthomas23
ianthomas23 committed Aug 15, 2012
commit 7c7b0372e3fab05b79cd72e822a1658fb80e7fee
57 changes: 40 additions & 17 deletions lib/matplotlib/tri/tripcolor.py
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Expand Up @@ -28,12 +28,19 @@ def tripcolor(ax, *args, **kwargs):
:class:`~matplotlib.tri.Triangulation` for a explanation of these
possibilities.

The next argument must be *C*, the array of color values, one per
point in the triangulation.

*shading* may be 'flat', 'faceted' or 'gouraud'. If *shading* is
'flat' or 'faceted', the colors used for each triangle are from
the mean C of the triangle's three points.
The next argument must be *C*, the array of color values, either
one per point in the triangulation if color values are defined at
points, or one per triangle in the triangulation if color values
are defined at triangles. If there are the same number of points
and triangles in the triangulation it is assumed that color
values are defined at points unless the kwarg *colorpoints* is
set to *False*.

*shading* may be 'flat' (the default), 'faceted' or 'gouraud'. If
*shading* is 'flat' or 'faceted' and C values are defined at
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Note that elsewhere in pcolormesh, the faceted option has been deprecated for some time and recently removed in favor of respecting the edgecolors kwarg. Does that make sense to do here as well?

points, the color values used for each triangle are from the mean
C of the triangle's three points. If *shading* is 'gouraud' then
color values must be defined at triangles.

The remaining kwargs are the same as for
:meth:`~matplotlib.axes.Axes.pcolor`.
Expand All @@ -50,20 +57,28 @@ def tripcolor(ax, *args, **kwargs):
vmin = kwargs.pop('vmin', None)
vmax = kwargs.pop('vmax', None)
shading = kwargs.pop('shading', 'flat')
colorpoints = kwargs.pop('colorpoints', True)

tri, args, kwargs = Triangulation.get_from_args_and_kwargs(*args, **kwargs)
x = tri.x
y = tri.y
triangles = tri.get_masked_triangles()

C = np.asarray(args[0])
if C.shape != x.shape:
raise ValueError('C array must have same length as triangulation x and'
' y arrays')

if shading == 'gouraud':
if len(C) != len(tri.x):
raise ValueError('For gouraud shading, the length of C '
'array must be the same as the number of '
'triangulation points')
collection = TriMesh(tri, **kwargs)
else:
if len(C) != len(tri.x) and len(C) != len(tri.triangles):
raise ValueError('Length of C array must be the same as either '
'the number of triangulation points or triangles')

# CAtPoints is True if C defined at points
# or False if C defined at triangles.
CAtPoints = (len(C) == len(tri.x))
if len(C) == len(tri.x) and len(C) == len(tri.triangles):
CAtPoints = colorpoints

if shading == 'faceted':
edgecolors = (0,0,0,1),
linewidths = (0.25,)
Expand All @@ -75,10 +90,18 @@ def tripcolor(ax, *args, **kwargs):
kwargs.setdefault('linewidths', linewidths)

# Vertices of triangles.
verts = np.concatenate((x[triangles][...,np.newaxis],
y[triangles][...,np.newaxis]), axis=2)
# Color values, one per triangle, mean of the 3 vertex color values.
C = C[triangles].mean(axis=1)
maskedTris = tri.get_masked_triangles()
verts = np.concatenate((tri.x[maskedTris][...,np.newaxis],
tri.y[maskedTris][...,np.newaxis]), axis=2)

# Color values.
if CAtPoints:
# One color per triangle, the mean of the 3 vertex color values.
C = C[maskedTris].mean(axis=1)
elif tri.mask is not None:
# Remove color values of masked triangles.
C = C.compress(1-tri.mask)

collection = PolyCollection(verts, **kwargs)

collection.set_alpha(alpha)
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