Changed from lists to Grouper

lib/matplotlib/axis.py

@@ -692,7 +692,6 @@ def __init__(self, axes, pickradius=15):
 
         self._autolabelpos = True
         self._smart_bounds = False
-        self._align_label_siblings = [self]
 
         self.label = self._get_label()
         self.labelpad = rcParams['axes.labelpad']
@@ -1673,22 +1672,14 @@ def set_ticks(self, ticks, minor=False):
             self.set_major_locator(mticker.FixedLocator(ticks))
             return self.get_major_ticks(len(ticks))
 
-    def _get_tick_boxes_siblings(self, renderer):
+    def _get_tick_boxes_siblings(self, xdir, renderer):
         """
         Get the bounding boxes for this `.axis` and its siblings
         as set by `.Figure.align_xlabels` or  `.Figure.align_ylablels`.
 
         By default it just gets bboxes for self.
         """
-        bboxes = []
-        bboxes2 = []
-        # if we want to align labels from other axes:
-        for axx in self._align_label_siblings:
-            ticks_to_draw = axx._update_ticks(renderer)
-            tlb, tlb2 = axx._get_tick_bboxes(ticks_to_draw, renderer)
-            bboxes.extend(tlb)
-            bboxes2.extend(tlb2)
-        return bboxes, bboxes2
+        raise NotImplementedError('Derived must override')
 
     def _update_label_position(self, renderer):
         """
@@ -1866,6 +1857,24 @@ def set_label_position(self, position):
         self.label_position = position
         self.stale = True
 
+    def _get_tick_boxes_siblings(self, renderer):
+        """
+        Get the bounding boxes for this `.axis` and its siblings
+        as set by `.Figure.align_xlabels` or  `.Figure.align_ylablels`.
+
+        By default it just gets bboxes for self.
+        """
+        bboxes = []
+        bboxes2 = []
+        grp = self.figure._align_xlabel_grp
+        # if we want to align labels from other axes:
+        for axx in grp.get_siblings(self.axes):
+            ticks_to_draw = axx.xaxis._update_ticks(renderer)
+            tlb, tlb2 = axx.xaxis._get_tick_bboxes(ticks_to_draw, renderer)
+            bboxes.extend(tlb)
+            bboxes2.extend(tlb2)
+        return bboxes, bboxes2
+
     def _update_label_position(self, renderer):
         """
         Update the label position based on the bounding box enclosing
@@ -1876,7 +1885,7 @@ def _update_label_position(self, renderer):
 
         # get bounding boxes for this axis and any siblings
         # that have been set by `fig.align_xlabels()`
-        bboxes, bboxes2 = self._get_tick_boxes_siblings(renderer)
+        bboxes, bboxes2 = self._get_tick_boxes_siblings(renderer=renderer)
 
         x, y = self.label.get_position()
         if self.label_position == 'bottom':
@@ -2216,6 +2225,24 @@ def set_label_position(self, position):
         self.label_position = position
         self.stale = True
 
+    def _get_tick_boxes_siblings(self, renderer):
+        """
+        Get the bounding boxes for this `.axis` and its siblings
+        as set by `.Figure.align_xlabels` or  `.Figure.align_ylablels`.
+
+        By default it just gets bboxes for self.
+        """
+        bboxes = []
+        bboxes2 = []
+        grp = self.figure._align_ylabel_grp
+        # if we want to align labels from other axes:
+        for axx in grp.get_siblings(self.axes):
+            ticks_to_draw = axx.yaxis._update_ticks(renderer)
+            tlb, tlb2 = axx.yaxis._get_tick_bboxes(ticks_to_draw, renderer)
+            bboxes.extend(tlb)
+            bboxes2.extend(tlb2)
+        return bboxes, bboxes2
+
     def _update_label_position(self, renderer):
         """
         Update the label position based on the bounding box enclosing
@@ -2226,7 +2253,7 @@ def _update_label_position(self, renderer):
 
         # get bounding boxes for this axis and any siblings
         # that have been set by `fig.align_ylabels()`
-        bboxes, bboxes2 = self._get_tick_boxes_siblings(renderer)
+        bboxes, bboxes2 = self._get_tick_boxes_siblings(renderer=renderer)
 
         x, y = self.label.get_position()
         if self.label_position == 'left':

lib/matplotlib/figure.py

@@ -380,6 +380,10 @@ def __init__(self,
         self.clf()
         self._cachedRenderer = None
 
+        # groupers to keep track of x and y labels we want to align.
+        self._align_xlabel_grp = cbook.Grouper()
+        self._align_ylabel_grp = cbook.Grouper()
+
     @property
     @cbook.deprecated("2.1", alternative="Figure.patch")
     def figurePatch(self):
@@ -2103,6 +2107,11 @@ def align_xlabels(self, axs=None):
             Optional list of (or ndarray) `~matplotlib.axes.Axes` to align
             the xlabels.  Default is to align all axes on the figure.
 
+        Note
+        ----
+        This assumes that ``axs`` are from the same `~.GridSpec`, so that
+        their `~.SubplotSpec` positions correspond to figure positions.
+
         See Also
         --------
         matplotlib.figure.Figure.align_ylabels
@@ -2124,7 +2133,6 @@ def align_xlabels(self, axs=None):
 
         if axs is None:
             axs = self.axes
-
         axs = np.asarray(np.array(axs)).flatten().tolist()
 
         for ax in axs:
@@ -2136,7 +2144,7 @@ def align_xlabels(self, axs=None):
             # loop through other axes, and search for label positions
             # that are same as this one, and that share the appropriate
             # row number.
-            #  Add to a list associated with each axes of sibblings.
+            #  Add to a grouper associated with each axes of sibblings.
             # This list is inspected in `axis.draw` by
             # `axis._update_label_position`.
             for axc in axs:
@@ -2146,7 +2154,8 @@ def align_xlabels(self, axs=None):
                             ss.get_rows_columns()
                     if (labpo == 'bottom' and rowc1 == row1 or
                         labpo == 'top' and rowc0 == row0):
-                        axc.xaxis._align_label_siblings += [ax.xaxis]
+                        # grouper for groups of xlabels to align
+                        self._align_xlabel_grp.join(ax, axc)
 
     def align_ylabels(self, axs=None):
         """
@@ -2167,6 +2176,11 @@ def align_ylabels(self, axs=None):
             Optional list (or ndarray) of `~matplotlib.axes.Axes` to align
             the ylabels. Default is to align all axes on the figure.
 
+        Note
+        ----
+        This assumes that ``axs`` are from the same `~.GridSpec`, so that
+        their `~.SubplotSpec` positions correspond to figure positions.
+
         See Also
         --------
         matplotlib.figure.Figure.align_xlabels
@@ -2187,7 +2201,6 @@ def align_ylabels(self, axs=None):
 
         if axs is None:
             axs = self.axes
-
         axs = np.asarray(np.array(axs)).flatten().tolist()
         for ax in axs:
             _log.debug(' Working on: %s', ax.get_ylabel())
@@ -2209,7 +2222,8 @@ def align_ylabels(self, axs=None):
                                 ss.get_rows_columns()
                         if (labpo == 'left' and colc0 == col0 or
                             labpo == 'right' and colc1 == col1):
-                            axc.yaxis._align_label_siblings += [ax.yaxis]
+                            # grouper for groups of ylabels to align
+                            self._align_ylabel_grp.join(ax, axc)
 
     def align_labels(self, axs=None):
         """