Merge pull request #4852 from jenshnielsen/nullstrideswireframe

ENH: Null strides wireframe

Author: tacaswell

doc/users/whats_new/wireframe3d.rst

@@ -0,0 +1,14 @@
+Zero r/cstride support in plot_wireframe
+----------------------------------------
+
+Adam Hughes added support to mplot3d's plot_wireframe to draw only row or
+column line plots. 
+
+
+Example::
+
+    from mpl_toolkits.mplot3d import Axes3D, axes3d
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    X, Y, Z = axes3d.get_test_data(0.05)
+    ax.plot_wireframe(X, Y, Z, rstride=10, cstride=0)

examples/mplot3d/wire3d_zero_stride.py

@@ -0,0 +1,12 @@
+from mpl_toolkits.mplot3d import axes3d
+import matplotlib.pyplot as plt
+import numpy as np
+
+fig, [ax1, ax2] = plt.subplots(2, 1, figsize=(8, 12), subplot_kw={'projection': '3d'})
+X, Y, Z = axes3d.get_test_data(0.05)
+ax1.plot_wireframe(X, Y, Z, rstride=10, cstride=0)
+ax1.set_title("Column stride 0")
+ax2.plot_wireframe(X, Y, Z, rstride=0, cstride=10)
+ax2.set_title("Row stride 0")
+plt.tight_layout()
+plt.show()

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -1717,7 +1717,9 @@ def plot_wireframe(self, X, Y, Z, *args, **kwargs):
         Plot a 3D wireframe.
 
         The `rstride` and `cstride` kwargs set the stride used to
-        sample the input data to generate the graph.
+        sample the input data to generate the graph. If either is 0
+        the input data in not sampled along this direction producing a 
+        3D line plot rather than a wireframe plot.
 
         ==========  ================================================
         Argument    Description
@@ -1748,14 +1750,23 @@ def plot_wireframe(self, X, Y, Z, *args, **kwargs):
         # This transpose will make it easy to obtain the columns.
         tX, tY, tZ = np.transpose(X), np.transpose(Y), np.transpose(Z)
 
-        rii = list(xrange(0, rows, rstride))
-        cii = list(xrange(0, cols, cstride))
+        if rstride:
+            rii = list(xrange(0, rows, rstride))
+            # Add the last index only if needed
+            if rows > 0 and rii[-1] != (rows - 1) :
+                rii += [rows-1]
+        else:
+            rii = []
+        if cstride:
+            cii = list(xrange(0, cols, cstride))
+            # Add the last index only if needed
+            if cols > 0 and cii[-1] != (cols - 1) :
+                cii += [cols-1]
+        else:
+            cii = []
 
-        # Add the last index only if needed
-        if rows > 0 and rii[-1] != (rows - 1) :
-            rii += [rows-1]
-        if cols > 0 and cii[-1] != (cols - 1) :
-            cii += [cols-1]
+        if rstride == 0 and cstride == 0:
+            raise ValueError("Either rstride or cstride must be non zero")
 
         # If the inputs were empty, then just
         # reset everything.

lib/mpl_toolkits/tests/baseline_images/test_mplot3d/wireframe3dzerocstride.png

@@ -1,6 +1,9 @@
+import sys
+import nose
+from nose.tools import assert_raises
 from mpl_toolkits.mplot3d import Axes3D, axes3d
 from matplotlib import cm
-from matplotlib.testing.decorators import image_comparison
+from matplotlib.testing.decorators import image_comparison, cleanup
 import matplotlib.pyplot as plt
 import numpy as np
 
@@ -172,6 +175,34 @@ def test_wireframe3d():
     ax.plot_wireframe(X, Y, Z, rstride=10, cstride=10)
 
 
+@image_comparison(baseline_images=['wireframe3dzerocstride'], remove_text=True,
+                  extensions=['png'])
+def test_wireframe3dzerocstride():
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    X, Y, Z = axes3d.get_test_data(0.05)
+    ax.plot_wireframe(X, Y, Z, rstride=10, cstride=0)
+
+
+@image_comparison(baseline_images=['wireframe3dzerorstride'], remove_text=True,
+                  extensions=['png'])
+def test_wireframe3dzerorstride():
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    X, Y, Z = axes3d.get_test_data(0.05)
+    ax.plot_wireframe(X, Y, Z, rstride=0, cstride=10)
+
+@cleanup
+def test_wireframe3dzerostrideraises():
+    if sys.version_info[:2] < (2, 7):
+        raise nose.SkipTest("assert_raises as context manager "
+                            "not supported with Python < 2.7")
+    fig = plt.figure()
+    ax = fig.add_subplot(111, projection='3d')
+    X, Y, Z = axes3d.get_test_data(0.05)
+    with assert_raises(ValueError):
+        ax.plot_wireframe(X, Y, Z, rstride=0, cstride=0)
+
 @image_comparison(baseline_images=['quiver3d'], remove_text=True)
 def test_quiver3d():
     fig = plt.figure()