ENH: add secondary x axis

jklymak · jklymak · commit b58217b15ef8 · 2018-07-10T10:39:08.000-07:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -38,6 +38,7 @@
     safe_first_element)
 from matplotlib.container import BarContainer, ErrorbarContainer, StemContainer
 from matplotlib.axes._base import _AxesBase, _process_plot_format
+from matplotlib.axes._secondary_axes import Secondary_Xaxis
 
 _log = logging.getLogger(__name__)
 
@@ -639,7 +640,7 @@ def indicate_inset_zoom(self, inset_ax, **kwargs):
 
         return rectpatch, connects
 
-    def secondary_xaxis(self, loc, conversion, *, **kwargs):
+    def secondary_xaxis(self, loc, conversion, **kwargs):
         """
         Add a second x-axis to this axes.
 
@@ -675,6 +676,7 @@ def secondary_xaxis(self, loc, conversion, *, **kwargs):
         """
         secondary_ax = Secondary_Xaxis(self, loc, conversion, **kwargs)
         self.add_child_axes(secondary_ax)
+        return secondary_ax
 
 
     def text(self, x, y, s, fontdict=None, withdash=False, **kwargs):
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -2510,7 +2510,16 @@ def _update_title_position(self, renderer):
             y = 1.0
             # need to check all our twins too...
             axs = self._twinned_axes.get_siblings(self)
-
+            # and all the children
+            for ax in self.child_axes:
+                if ax is not None:
+                    locator = ax.get_axes_locator()
+                    if locator:
+                        pos = locator(self, renderer)
+                        ax.apply_aspect(pos)
+                    else:
+                        ax.apply_aspect()
+                    axs = axs + [ax]
             for ax in axs:
                 try:
                     if (ax.xaxis.get_label_position() == 'top'
@@ -2542,12 +2551,15 @@ def draw(self, renderer=None, inframe=False):
 
         # prevent triggering call backs during the draw process
         self._stale = True
-        locator = self.get_axes_locator()
-        if locator:
-            pos = locator(self, renderer)
-            self.apply_aspect(pos)
-        else:
-            self.apply_aspect()
+
+        # loop over self and child axes...
+        for ax in [self]:
+            locator = ax.get_axes_locator()
+            if locator:
+                pos = locator(self, renderer)
+                ax.apply_aspect(pos)
+            else:
+                ax.apply_aspect()
 
         artists = self.get_children()
         artists.remove(self.patch)
