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Support RGBA for quadmesh mode of pcolorfast. #13986

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Merged
merged 1 commit into from
Apr 23, 2019
Merged

Support RGBA for quadmesh mode of pcolorfast. #13986

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4 changes: 1 addition & 3 deletions doc/api/api_changes/2019-02-11-PGE.rst
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Original file line number Diff line number Diff line change
@@ -1,6 +1,4 @@
Added support for RGB(A) images in pcolorfast
`````````````````````````````````````````````

pcolorfast now accepts 3D images (RGB or RGBA) arrays if the X and Y
specifications allow image or pcolorimage rendering; they remain unsupported by
the more general quadmesh rendering
pcolorfast now accepts 3D images (RGB or RGBA) arrays.
36 changes: 22 additions & 14 deletions lib/matplotlib/axes/_axes.py
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Expand Up @@ -6191,12 +6191,18 @@ def pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None,
Parameters
----------
C : array-like(M, N)
A 2D array or masked array. The values will be color-mapped.
This argument can only be passed positionally.
The image data. Supported array shapes are:

C can in some cases be 3D with the last dimension as rgb(a).
This is available when C qualifies for image or pcolorimage type,
will throw a TypeError if C is 3D and quadmesh.
- (M, N): an image with scalar data. The data is visualized
using a colormap.
- (M, N, 3): an image with RGB values (0-1 float or 0-255 int).
- (M, N, 4): an image with RGBA values (0-1 float or 0-255 int),
i.e. including transparency.

The first two dimensions (M, N) define the rows and columns of
the image.

This parameter can only be passed positionally.

X, Y : tuple or array-like, default: ``(0, N)``, ``(0, M)``
*X* and *Y* are used to specify the coordinates of the
Expand All @@ -6221,9 +6227,9 @@ def pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None,
- Use 2D arrays *X*, *Y* if you need an *arbitrary quadrilateral
grid* (i.e. if the quadrilaterals are not rectangular).

In this case *X* and *Y* are 2D arrays with shape (M, N),
In this case *X* and *Y* are 2D arrays with shape (M + 1, N + 1),
specifying the x and y coordinates of the corners of the colored
quadrilaterals. See `~.Axes.pcolormesh` for details.
quadrilaterals.

This is the most general, but the slowest to render. It may
produce faster and more compact output using ps, pdf, and
Expand Down Expand Up @@ -6292,10 +6298,6 @@ def pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None,
else:
style = "pcolorimage"
elif x.ndim == 2 and y.ndim == 2:
if C.ndim > 2:
raise ValueError(
'pcolorfast needs to use quadmesh, '
'which is not supported when x and y are 2D and C 3D')
style = "quadmesh"
else:
raise TypeError("arguments do not match valid signatures")
Expand All @@ -6305,9 +6307,15 @@ def pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None,
if style == "quadmesh":
# data point in each cell is value at lower left corner
coords = np.stack([x, y], axis=-1)
if np.ndim(C) == 2:
qm_kwargs = {"array": np.ma.ravel(C)}
elif np.ndim(C) == 3:
qm_kwargs = {"color": np.ma.reshape(C, (-1, C.shape[-1]))}
else:
raise ValueError("C must be 2D or 3D")
collection = mcoll.QuadMesh(
nc, nr, coords,
array=np.ma.ravel(C), alpha=alpha, cmap=cmap, norm=norm,
nc, nr, coords, **qm_kwargs,
alpha=alpha, cmap=cmap, norm=norm,
antialiased=False, edgecolors="none")
self.add_collection(collection, autolim=False)
xl, xr, yb, yt = x.min(), x.max(), y.min(), y.max()
Expand All @@ -6331,7 +6339,7 @@ def pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None,

if vmin is not None or vmax is not None:
ret.set_clim(vmin, vmax)
else:
elif np.ndim(C) == 2: # C.ndim == 3 is RGB(A) so doesn't need scaling.
ret.autoscale_None()
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I would add a comment

# np.dim(C) == 3 has explicit RGB(A) values and does not need scaling.

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sure, done

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Have you pushed? I don't see a comment.

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duh, put it at the wrong line; fixed.


ret.sticky_edges.x[:] = [xl, xr]
Expand Down
21 changes: 4 additions & 17 deletions lib/matplotlib/tests/test_axes.py
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Expand Up @@ -5151,27 +5151,14 @@ def test_no_None():
mpl.collections.QuadMesh),
]
)
def test_pcolorfast_colormapped(xy, cls):
@pytest.mark.parametrize(
"data", [np.arange(12).reshape((3, 4)), np.random.rand(3, 4, 3)]
)
def test_pcolorfast(xy, data, cls):
fig, ax = plt.subplots()
data = np.arange(12).reshape((3, 4))
assert type(ax.pcolorfast(*xy, data)) == cls


def test_pcolor_fast_RGB():

fig, ax = plt.subplots(1, 1)

np.random.seed(19680801)
C = np.random.rand(10, 10, 3) # RGB image [0,1]
x = np.arange(11, dtype=np.float)
y = np.arange(11, dtype=np.float)

xv, yv = np.meshgrid(x, y)

with pytest.raises(ValueError):
ax.pcolorfast(xv, yv, C)


def test_shared_scale():
fig, axs = plt.subplots(2, 2, sharex=True, sharey=True)

Expand Down