FIX: allow secondary axes to be non-linear

jklymak · jklymak · commit 7ca6b493c3eb · 2019-06-26T21:56:08.000-07:00
diff --git a/lib/matplotlib/axes/_secondary_axes.py b/lib/matplotlib/axes/_secondary_axes.py
@@ -222,7 +222,8 @@ def set_functions(self, functions):
                              'must be a two-tuple of callable functions '
                              'with the first function being the transform '
                              'and the second being the inverse')
-        set_scale(defscale, functions=self._functions)
+        # need to invert the roles here for the ticks to line up.  
+        set_scale(defscale, functions=self._functions[::-1])
 
     def draw(self, renderer=None, inframe=False):
         """
@@ -262,7 +263,8 @@ def _set_scale(self):
         if self._ticks_set:
             ticks = self._axis.get_ticklocs()
 
-        set_scale(defscale, functions=self._functions)
+        # need to invert the roles here for the ticks to line up.
+        set_scale(defscale, functions=self._functions[::-1])
 
         # OK, set_scale sets the locators, but if we've called
         # axsecond.set_ticks, we want to keep those.
