Pull request fixing the long standing issue #1317

paalge · anntzer · commit a9801b65c093 · 2019-03-05T14:05:05.000+01:00
Added doc string and raise of error for quadmesh

Added test for RGB image in pcolorfast

Added doc changes per efirings comments

Doc change and use of pytest.raises

Changed from TypeError to ValueError

Removed whitespace

Doc changes in response to comments

Doc modified
diff --git a/doc/api/api_changes/2019-02-11-PGE.rst b/doc/api/api_changes/2019-02-11-PGE.rst
@@ -0,0 +1,6 @@
+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
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -6185,6 +6185,10 @@ def pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None,
             A 2D array or masked array. The values will be color-mapped.
             This argument can only be passed positionally.
 
+            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.
+
         X, Y : tuple or array-like, default: ``(0, N)``, ``(0, M)``
             *X* and *Y* are used to specify the coordinates of the
             quadrilaterals. There are different ways to do this:
@@ -6258,7 +6262,7 @@ def pcolorfast(self, *args, alpha=None, norm=None, cmap=None, vmin=None,
                 "'norm' must be an instance of 'mcolors.Normalize'")
 
         C = args[-1]
-        nr, nc = np.shape(C)
+        nr, nc = np.shape(C)[:2]
         if len(args) == 1:
             style = "image"
             x = [0, nc]
@@ -6279,6 +6283,10 @@ 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")
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -5184,6 +5184,21 @@ def test_pcolorfast_colormapped(xy, cls):
     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)
 
