Fix panel sharing issue with stacked panels

Author: lukelbd

docs/insets_panels.py

@@ -27,10 +27,9 @@
 #
 # It is often useful to have narrow "panels" along the edge of a larger
 # subplot for plotting secondary 1-dimensional datasets or summary statistics.
-# In matplotlib, there is no simple way to do this. In ProPlot, you can
-# create panels by passing a location (e.g. ``loc='r'`` or ``loc='right'``)
-# to the `~proplot.axes.Axes.panel` or `~proplot.axes.Axes.panel_axes` methods.
-# The resulting axes are instances of `~proplot.axes.CartesianAxes`.
+# In ProPlot, you can create panels by passing a location (e.g. ``loc='r'`` or
+# ``loc='right'``) to the `~proplot.axes.Axes.panel` or `~proplot.axes.Axes.panel_axes`
+# methods. The resulting axes are instances of `~proplot.axes.CartesianAxes`.
 #
 # To generate "stacked" panels, simply call `~proplot.axes.Axes.panel` more
 # than once. To include panels when centering spanning axis labels and super
@@ -100,8 +99,7 @@
 axs.format(
     xlim=(0, 1), ylim=(0, 1),
     xlabel='xlabel', ylabel='ylabel',
-    yticks=plot.arange(0.2, 0.8, 0.2),
-    xticks=plot.arange(0.2, 0.8, 0.2),
+    xticks=0.2, yticks=0.2,
     title='Title', suptitle='Complex arrangement of panels',
     collabels=['Column 1', 'Column 2'],
     abc=True, abcloc='ul', titleloc='uc', abovetop=False,

proplot/axes/base.py

@@ -435,11 +435,15 @@ def _is_panel(self):
         """
         return bool(self._panel_parent)
 
-    def _is_panel_parent_or_child(self, other):
+    def _is_panel_group_member(self, other):
         """
         Return whether the axes are related.
         """
-        return self._panel_parent is other or other._panel_parent is self
+        return (
+            self._panel_parent is other  # child
+            or other._panel_parent is self   # parent
+            or other._panel_parent is self._panel_parent  # sibling
+        )
 
     def _loc_translate(self, loc, mode=None, allow_manual=True):
         """

proplot/axes/cartesian.py

@@ -268,6 +268,9 @@ def _apply_axis_sharing(self):
         at drawtime, "shared" labels can be inadvertantly turned off.
         """
         # X axis
+        # NOTE: The "panel sharing group" refers to axes and panels *above* the
+        # bottommost or to the *right* of the leftmost panel. But the edge panel
+        # sharing level is the *figure* sharing level.
         axis = self.xaxis
         if self._sharex is not None:
             level = 3 if self._panel_sharex_group else self.figure._sharex
@@ -372,7 +375,7 @@ def _sharex_setup(self, sharex):
 
         # Get sharing level
         level = (
-            3 if self._panel_sharex_group and self._is_panel_parent_or_child(sharex)
+            3 if self._panel_sharex_group and self._is_panel_group_member(sharex)
             else self.figure._sharex
         )
         if level not in range(4):
@@ -431,7 +434,7 @@ def _sharey_setup(self, sharey):
 
         # Get sharing level
         level = (
-            3 if self._panel_sharey_group and self._is_panel_parent_or_child(sharey)
+            3 if self._panel_sharey_group and self._is_panel_group_member(sharey)
             else self.figure._sharey
         )
         if level not in range(4):