Add comment, and additional text to docstring.

efiring · efiring · commit 84e44e6531eb · 2018-07-02T10:49:11.000-04:00
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -1173,6 +1173,9 @@ def _autolev(self, N):
         """
         Select contour levels to span the data.
 
+        The target number of levels, *N*, is used only when the
+        scale is not log and default locator is used.
+
         We need two more levels for filled contours than for
         line contours, because for the latter we need to specify
         the lower and upper boundary of each range. For example,
@@ -1195,6 +1198,7 @@ def _autolev(self, N):
         except AttributeError:
             pass
 
+        # Trim excess levels the locator may have supplied.
         under = np.nonzero(lev < self.zmin)[0]
         i0 = under[-1] if len(under) else 0
         over = np.nonzero(lev > self.zmax)[0]
