Support moving axes to the opposite side of the panel

doc/changelog.qmd

@@ -44,6 +44,22 @@ title: Changelog
 - Added [](:class:`~plotnine.composition.inset_element`) with which you can insert plot
   compositions or images into another plot.
 
+- Position scales gained a `position` parameter, so you can move an axis to the
+  opposite side of the panel. Use `position="top"` for the x axis and
+  `position="right"` for the y axis.
+
+  ```python
+  ggplot(df, aes("x", "y")) + geom_point() + scale_x_continuous(position="top")
+  ```
+
+  Each axis side can be styled independently with new per-side themeables, e.g.
+  `axis_text_x_top`, `axis_title_y_right`, `axis_line_x_top` and
+  `axis_ticks_major_y_right`.
+
+  ```python
+  theme(axis_text_x_top=element_text(color="blue"))
+  ```
+
 ### API Changes
 
 - Removed `geom.to_layer()`, `stat.to_layer()`, `annotate.to_layer()`,

plotnine/_mpl/layout_manager/_layout_tree.py

@@ -552,7 +552,12 @@ def align_axis_titles(self):
         def axis_title_clearance(s):
             return s.axis_title_clearance
 
-        for spaces in [self.bottom_spaces, self.left_spaces]:
+        for spaces in [
+            self.bottom_spaces,
+            self.left_spaces,
+            self.top_spaces,
+            self.right_spaces,
+        ]:
             _align(spaces, axis_title_clearance, "axis_title_alignment")
 
         for tree in self.sub_compositions: