Code review comments

scottshambaugh · scottshambaugh · commit b88c8a1cb9c8 · 2024-06-16T18:44:12.000-06:00
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -1987,13 +1987,14 @@ def fill_between(self, x1, y1, z1, x2, y2, z2, *,
 
         mode : {'quad', 'polygon', 'auto'}, default: 'auto'
             The fill mode. One of:
+
             - 'quad':  A separate quadrilateral polygon is created for each
               pair of subsequent points in the two lines.
             - 'polygon': The two lines are connected to form a single polygon.
               This is faster and can render more cleanly for simple shapes
               (e.g. for filling between two lines that lie within a plane).
             - 'auto': If the lines are in a plane parallel to a coordinate axis
-              (one of *x*, *y*, *z* for both lines are constant and equal),
+              (one of *x*, *y*, *z* are constant and equal for both lines),
               'polygon' is used. Otherwise, 'quad' is used.
 
         **kwargs
@@ -2028,29 +2029,29 @@ def fill_between(self, x1, y1, z1, x2, y2, z2, *,
 
         polys = []
         for idx0, idx1 in cbook.contiguous_regions(where):
-            x1slice = x1[idx0:idx1]
-            y1slice = y1[idx0:idx1]
-            z1slice = z1[idx0:idx1]
-            x2slice = x2[idx0:idx1]
-            y2slice = y2[idx0:idx1]
-            z2slice = z2[idx0:idx1]
-
-            if not len(x1slice):
+            x1i = x1[idx0:idx1]
+            y1i = y1[idx0:idx1]
+            z1i = z1[idx0:idx1]
+            x2i = x2[idx0:idx1]
+            y2i = y2[idx0:idx1]
+            z2i = z2[idx0:idx1]
+
+            if not len(x1i):
                 continue
 
             if mode == 'quad':
-                for i in range(len(x1slice) - 1):
-                    poly = [(x1slice[i], y1slice[i], z1slice[i]),
-                            (x1slice[i+1], y1slice[i+1], z1slice[i+1]),
-                            (x2slice[i+1], y2slice[i+1], z2slice[i+1]),
-                            (x2slice[i], y2slice[i], z2slice[i])]
-                    polys.append(poly)
+                # Preallocate the array for the region's vertices, and fill it in
+                n_polys_i = len(x1i) - 1
+                polys_i = np.empty((n_polys_i, 4, 3))
+                polys_i[:, 0, :] = np.column_stack((x1i[:-1], y1i[:-1], z1i[:-1]))
+                polys_i[:, 1, :] = np.column_stack((x1i[1:], y1i[1:], z1i[1:]))
+                polys_i[:, 2, :] = np.column_stack((x2i[1:], y2i[1:], z2i[1:]))
+                polys_i[:, 3, :] = np.column_stack((x2i[:-1], y2i[:-1], z2i[:-1]))
+                polys = polys + [*polys_i]
             elif mode == 'polygon':
-                poly = []
-                for i in range(len(x1slice)):
-                    poly.append((x1slice[i], y1slice[i], z1slice[i]))
-                for i in range(len(x2slice) - 1, -1, -1):
-                    poly.append((x2slice[i], y2slice[i], z2slice[i]))
+                line1 = np.column_stack((x1i, y1i, z1i))
+                line2 = np.column_stack((x2i[::-1], y2i[::-1], z2i[::-1]))
+                poly = np.concatenate((line1, line2), axis=0)
                 polys.append(poly)
 
         polyc = art3d.Poly3DCollection(polys, **kwargs)
