FIX: Axes.indicate_inset failure

clbarnes · clbarnes · commit 5bac8601ac28 · 2019-05-20T13:56:31.000-04:00
See #14275. inset_ax argument should be optional, but was failing because it tried to return a variable which was not defined. This is now fixed.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -531,7 +531,8 @@ def indicate_inset(self, bounds, inset_ax=None, *, transform=None,
              Rectangle artist.
 
         connector_lines : list of `.Patches.ConnectionPatch`
-            One for each of four connector lines.
+            One for each of four connector lines
+            (empty if *inset_ax* is *None*).
             Two are set with visibility to *False*,
             but the user can set the visibility to *True* if the
             automatic choice is not deemed correct.
@@ -552,19 +553,24 @@ def indicate_inset(self, bounds, inset_ax=None, *, transform=None,
                 zorder=zorder,  label=label, transform=transform, **kwargs)
         self.add_patch(rectpatch)
 
+        connects = []
+
         if inset_ax is not None:
             # want to connect the indicator to the rect....
-            connects = []
             xr = [bounds[0], bounds[0]+bounds[2]]
             yr = [bounds[1], bounds[1]+bounds[3]]
             for xc in range(2):
                 for yc in range(2):
                     xyA = (xc, yc)
                     xyB = (xr[xc], yr[yc])
-                    connects += [mpatches.ConnectionPatch(xyA, xyB,
+                    connects.append(
+                        mpatches.ConnectionPatch(
+                            xyA, xyB,
                             'axes fraction', 'data',
                             axesA=inset_ax, axesB=self, arrowstyle="-",
-                            zorder=zorder, edgecolor=edgecolor, alpha=alpha)]
+                            zorder=zorder, edgecolor=edgecolor, alpha=alpha
+                        )
+                    )
                     self.add_patch(connects[-1])
             # decide which two of the lines to keep visible....
             pos = inset_ax.get_position()
