Merge branch 'mplot3d/empty_plots'

Author: WeatherGod

CHANGELOG

@@ -1,3 +1,6 @@
+2011-06-28 3D versions of scatter, plot, plot_wireframe, plot_surface,
+           bar3d, and some other functions now support empty inputs. - BVR
+
 2011-06-16 Added *bottom* keyword parameter for the stem command. 
            Also, implemented a legend handler for the stem plot. 
            - JJL

lib/mpl_toolkits/mplot3d/art3d.py

@@ -319,7 +319,10 @@ def do_3d_projection(self, renderer):
         self.set_edgecolors(zalpha(self._edgecolor3d, vzs))
         PatchCollection.set_offsets(self, zip(vxs, vys))
 
-        return min(vzs)
+        if vzs.size > 0 :
+            return min(vzs)
+        else :
+            return np.nan
 
     def draw(self, renderer):
         self._old_draw(renderer)
@@ -395,7 +398,13 @@ def get_vector(self, segments3d):
             ei = si+len(p)
             segis.append((si, ei))
             si = ei
-        xs, ys, zs = zip(*points)
+
+        if len(segments3d) > 0 :
+            xs, ys, zs = zip(*points)
+        else :
+            # We need this so that we can skip the bad unpacking from zip()
+            xs, ys, zs = [], [], []
+
         ones = np.ones(len(xs))
         self._vec = np.array([xs, ys, zs, ones])
         self._segis = segis
@@ -458,11 +467,16 @@ def do_3d_projection(self, renderer):
 
         # Return zorder value
         if self._sort_zpos is not None:
-           zvec = np.array([[0], [0], [self._sort_zpos], [1]])
-           ztrans = proj3d.proj_transform_vec(zvec, renderer.M)
-           return ztrans[2][0]
-        else:
+            zvec = np.array([[0], [0], [self._sort_zpos], [1]])
+            ztrans = proj3d.proj_transform_vec(zvec, renderer.M)
+            return ztrans[2][0]
+        elif tzs.size > 0 :
+            # FIXME: Some results still don't look quite right.
+            #        In particular, examine contourf3d_demo2.py
+            #        with az = -54 and elev = -45.
             return np.min(tzs)
+        else :
+            return np.nan
 
     def set_facecolor(self, colors):
         PolyCollection.set_facecolor(self, colors)
@@ -559,8 +573,9 @@ def get_colors(c, num):
 def zalpha(colors, zs):
     """Modify the alphas of the color list according to depth"""
     colors = get_colors(colors, len(zs))
-    norm = Normalize(min(zs), max(zs))
-    sats = 1 - norm(zs) * 0.7
-    colors = [(c[0], c[1], c[2], c[3] * s) for c, s in zip(colors, sats)]
+    if zs.size > 0 :
+        norm = Normalize(min(zs), max(zs))
+        sats = 1 - norm(zs) * 0.7
+        colors = [(c[0], c[1], c[2], c[3] * s) for c, s in zip(colors, sats)]
     return colors
 

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -670,17 +670,29 @@ def plot(self, xs, ys, *args, **kwargs):
         Other arguments are passed on to
         :func:`~matplotlib.axes.Axes.plot`
         '''
-
+        # FIXME: This argument parsing might be better handled
+        #        when we set later versions of python for
+        #        minimum requirements.  Currently at 2.4.
+        #        Note that some of the reason for the current difficulty
+        #        is caused by the fact that we want to insert a new
+        #        (semi-optional) positional argument 'Z' right before
+        #        many other traditional positional arguments occur
+        #        such as the color, linestyle and/or marker.
         had_data = self.has_data()
         zs = kwargs.pop('zs', 0)
         zdir = kwargs.pop('zdir', 'z')
 
         argsi = 0
         # First argument is array of zs
         if len(args) > 0 and cbook.iterable(args[0]) and \
-                len(xs) == len(args[0]) and cbook.is_scalar(args[0][0]):
-            zs = args[argsi]
-            argsi += 1
+                len(xs) == len(args[0]) :
+            # So, we know that it is an array with
+            # first dimension the same as xs.
+            # Next, check to see if the data contained
+            # therein (if any) is scalar (and not another array).
+            if len(args[0]) == 0 or cbook.is_scalar(args[0][0]) :
+                zs = args[argsi]
+                argsi += 1
 
         # First argument is z value
         elif len(args) > 0 and cbook.is_scalar(args[0]):
@@ -860,7 +872,7 @@ def _shade_colors(self, color, normals):
             colors = (0.5 + norm(shade)[:, np.newaxis] * 0.5) * color
             colors[:, 3] = alpha
         else:
-            colors = color.copy()
+            colors = np.asanyarray(color).copy()
 
         return colors
 
@@ -892,12 +904,37 @@ def plot_wireframe(self, X, Y, Z, *args, **kwargs):
         cstride = kwargs.pop("cstride", 1)
 
         had_data = self.has_data()
+        Z = np.atleast_2d(Z)
+        # FIXME: Support masked arrays
+        X = np.asarray(X)
+        Y = np.asarray(Y)
         rows, cols = Z.shape
-
+        # Force X and Y to take the same shape.
+        # If they can not be fitted to that shape,
+        # then an exception is automatically thrown.
+        X.shape = (rows, cols)
+        Y.shape = (rows, cols)
+
+        # We want two sets of lines, one running along the "rows" of
+        # Z and another set of lines running along the "columns" of Z.
+        # This transpose will make it easy to obtain the columns.
         tX, tY, tZ = np.transpose(X), np.transpose(Y), np.transpose(Z)
 
-        rii = [i for i in range(0, rows, rstride)]+[rows-1]
-        cii = [i for i in range(0, cols, cstride)]+[cols-1]
+        rii = range(0, rows, rstride)
+        cii = range(0, cols, cstride)
+
+        # 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 the inputs were empty, then just
+        # reset everything.
+        if Z.size == 0 :
+            rii = []
+            cii = []
+
         xlines = [X[i] for i in rii]
         ylines = [Y[i] for i in rii]
         zlines = [Z[i] for i in rii]
@@ -1133,16 +1170,21 @@ def add_collection3d(self, col, zs=0, zdir='z'):
             - LineColleciton
             - PatchCollection
         '''
+        zvals = np.atleast_1d(zs)
+        if len(zvals) > 0 :
+            zsortval = min(zvals)
+        else :
+            zsortval = 0   # FIXME: Fairly arbitrary. Is there a better value?
 
         if type(col) is collections.PolyCollection:
             art3d.poly_collection_2d_to_3d(col, zs=zs, zdir=zdir)
-            col.set_sort_zpos(min(zs))
+            col.set_sort_zpos(zsortval)
         elif type(col) is collections.LineCollection:
             art3d.line_collection_2d_to_3d(col, zs=zs, zdir=zdir)
-            col.set_sort_zpos(min(zs))
+            col.set_sort_zpos(zsortval)
         elif type(col) is collections.PatchCollection:
             art3d.patch_collection_2d_to_3d(col, zs=zs, zdir=zdir)
-            col.set_sort_zpos(min(zs))
+            col.set_sort_zpos(zsortval)
 
         Axes.add_collection(self, col)
 
@@ -1251,7 +1293,14 @@ def bar(self, left, height, zs=0, zdir='z', *args, **kwargs):
             if 'alpha' in kwargs:
                 p.set_alpha(kwargs['alpha'])
 
-        xs, ys = zip(*verts)
+        if len(verts) > 0 :
+            # the following has to be skipped if verts is empty
+            # NOTE: Bugs could still occur if len(verts) > 0,
+            #       but the "2nd dimension" is empty.
+            xs, ys = zip(*verts)
+        else :
+            xs, ys = [], []
+
         xs, ys, verts_zs = art3d.juggle_axes(xs, ys, verts_zs, zdir)
         self.auto_scale_xyz(xs, ys, verts_zs, had_data)
 
@@ -1317,6 +1366,7 @@ def bar3d(self, x, y, z, dx, dy, dz, color='b',
         if len(x) != len(y) or len(x) != len(z):
             warnings.warn('x, y, and z must be the same length.')
 
+        # FIXME: This is archaic and could be done much better.
         minx, miny, minz = 1e20, 1e20, 1e20
         maxx, maxy, maxz = -1e20, -1e20, -1e20