Replace path_length in contour

dstansby · dstansby · commit b4e339af4cc2 · 2017-09-16T12:18:54.000+01:00
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -376,7 +376,7 @@ def calc_label_rot_and_inline(self, slc, ind, lw, lc=None, spacing=5):
         not empty (lc defaults to the empty list if None).  *spacing*
         is the space around the label in pixels to leave empty.
 
-        Do both of these tasks at once to avoid calling mlab.path_length
+        Do both of these tasks at once to avoid calculating path lengths
         multiple times, which is relatively costly.
 
         The method used here involves calculating the path length
@@ -400,8 +400,10 @@ def calc_label_rot_and_inline(self, slc, ind, lw, lc=None, spacing=5):
 
             ind = 0
 
-        # Path length in pixel space
-        pl = mlab.path_length(slc)
+        # Calculate path lengths
+        pl = np.zeros(slc.shape[0], dtype=float)
+        dx = np.diff(slc, axis=0)
+        pl[1:] = np.cumsum(np.hypot(dx[:, 0], dx[:, 1]))
         pl = pl - pl[ind]
 
         # Use linear interpolation to get points around label
diff --git a/lib/matplotlib/mlab.py b/lib/matplotlib/mlab.py
@@ -3911,6 +3911,7 @@ def cross_from_above(x, threshold):
 ##################################################
 # Vector and path length geometry calculations
 ##################################################
+@cbook.deprecated('2.2')
 def vector_lengths(X, P=2., axis=None):
     """
     Finds the length of a set of vectors in *n* dimensions.  This is
@@ -3925,6 +3926,7 @@ def vector_lengths(X, P=2., axis=None):
     return (np.sum(X**(P), axis=axis))**(1./P)
 
 
+@cbook.deprecated('2.2')
 def distances_along_curve(X):
     """
     Computes the distance between a set of successive points in *N* dimensions.
@@ -3937,6 +3939,7 @@ def distances_along_curve(X):
     return vector_lengths(X, axis=1)
 
 
+@cbook.deprecated('2.2')
 def path_length(X):
     """
     Computes the distance travelled along a polygonal curve in *N* dimensions.
