Merge pull request #17754 from anntzer/contour2

timhoffm · web-flow · commit 3bbc78a3d53d · 2020-06-26T03:12:44.000+02:00
Small cleanups to contour() code.
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
@@ -248,14 +248,22 @@ class silent_list(list):
     one will get ::
 
         <a list of 3 Line2D objects>
+
+    If ``self.type`` is None, the type name is obtained from the first item in
+    the list (if any).
     """
+
     def __init__(self, type, seq=None):
         self.type = type
         if seq is not None:
             self.extend(seq)
 
     def __repr__(self):
-        return '<a list of %d %s objects>' % (len(self), self.type)
+        if self.type is not None or len(self) != 0:
+            tp = self.type if self.type is not None else type(self[0]).__name__
+            return f"<a list of {len(self)} {tp} objects>"
+        else:
+            return "<an empty list>"
 
 
 @deprecated("3.3")
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -845,10 +845,8 @@ def __init__(self, ax, *args,
                 if extend_max:
                     cmap.set_over(self.colors[-1])
 
-        if self.filled:
-            self.collections = cbook.silent_list('mcoll.PathCollection')
-        else:
-            self.collections = cbook.silent_list('mcoll.LineCollection')
+        self.collections = cbook.silent_list(None)
+
         # label lists must be initialized here
         self.labelTexts = []
         self.labelCValues = []
@@ -869,53 +867,48 @@ def __init__(self, ax, *args,
         if self.filled:
             if self.linewidths is not None:
                 cbook._warn_external('linewidths is ignored by contourf')
-
             # Lower and upper contour levels.
             lowers, uppers = self._get_lowers_and_uppers()
-
             # Ensure allkinds can be zipped below.
             if self.allkinds is None:
                 self.allkinds = [None] * len(self.allsegs)
-
             # Default zorder taken from Collection
             self._contour_zorder = kwargs.pop('zorder', 1)
-            for level, level_upper, segs, kinds in \
-                    zip(lowers, uppers, self.allsegs, self.allkinds):
-                paths = self._make_paths(segs, kinds)
 
-                col = mcoll.PathCollection(
-                    paths,
+            self.collections[:] = [
+                mcoll.PathCollection(
+                    self._make_paths(segs, kinds),
                     antialiaseds=(self.antialiased,),
                     edgecolors='none',
                     alpha=self.alpha,
                     transform=self.get_transform(),
                     zorder=self._contour_zorder)
-                self.axes.add_collection(col, autolim=False)
-                self.collections.append(col)
+                for level, level_upper, segs, kinds
+                in zip(lowers, uppers, self.allsegs, self.allkinds)]
         else:
-            tlinewidths = self._process_linewidths()
-            self.tlinewidths = tlinewidths
+            self.tlinewidths = tlinewidths = self._process_linewidths()
             tlinestyles = self._process_linestyles()
             aa = self.antialiased
             if aa is not None:
                 aa = (self.antialiased,)
             # Default zorder taken from LineCollection
             self._contour_zorder = kwargs.pop('zorder', 2)
-            for level, width, lstyle, segs in \
-                    zip(self.levels, tlinewidths, tlinestyles, self.allsegs):
-                col = mcoll.LineCollection(
+
+            self.collections[:] = [
+                mcoll.LineCollection(
                     segs,
                     antialiaseds=aa,
                     linewidths=width,
                     linestyles=[lstyle],
                     alpha=self.alpha,
                     transform=self.get_transform(),
-                    zorder=self._contour_zorder)
-                col.set_label('_nolegend_')
-                self.axes.add_collection(col, autolim=False)
-                self.collections.append(col)
+                    zorder=self._contour_zorder,
+                    label='_nolegend_')
+                for level, width, lstyle, segs
+                in zip(self.levels, tlinewidths, tlinestyles, self.allsegs)]
 
         for col in self.collections:
+            self.axes.add_collection(col, autolim=False)
             col.sticky_edges.x[:] = [self._mins[0], self._maxs[0]]
             col.sticky_edges.y[:] = [self._mins[1], self._maxs[1]]
         self.axes.update_datalim([self._mins, self._maxs])
