BUG: Fix for xlabel/ylabel in barh plot (#45145)

Author: stefmolin

doc/source/whatsnew/v1.5.0.rst

@@ -230,7 +230,7 @@ Period
 
 Plotting
 ^^^^^^^^
--
+- Bug in :meth:`DataFrame.plot.barh` that prevented labeling the x-axis and ``xlabel`` updating the y-axis label (:issue:`45144`)
 -
 
 Groupby/resample/rolling

pandas/plotting/_matplotlib/core.py

@@ -754,6 +754,10 @@ def _plot(cls, ax: Axes, x, y, style=None, is_errorbar: bool = False, **kwds):
             args = (x, y, style) if style is not None else (x, y)
             return ax.plot(*args, **kwds)
 
+    def _get_custom_index_name(self):
+        """Specify whether xlabel/ylabel should be used to override index name"""
+        return self.xlabel
+
     def _get_index_name(self) -> str | None:
         if isinstance(self.data.index, ABCMultiIndex):
             name = self.data.index.names
@@ -766,9 +770,10 @@ def _get_index_name(self) -> str | None:
             if name is not None:
                 name = pprint_thing(name)
 
-        # GH 9093, override the default xlabel if xlabel is provided.
-        if self.xlabel is not None:
-            name = pprint_thing(self.xlabel)
+        # GH 45145, override the default axis label if one is provided.
+        index_name = self._get_custom_index_name()
+        if index_name is not None:
+            name = pprint_thing(index_name)
 
         return name
 
@@ -1572,12 +1577,11 @@ def _post_plot_logic(self, ax: Axes, data):
             str_index = [pprint_thing(key) for key in data.index]
         else:
             str_index = [pprint_thing(key) for key in range(data.shape[0])]
-        name = self._get_index_name()
 
         s_edge = self.ax_pos[0] - 0.25 + self.lim_offset
         e_edge = self.ax_pos[-1] + 0.25 + self.bar_width + self.lim_offset
 
-        self._decorate_ticks(ax, name, str_index, s_edge, e_edge)
+        self._decorate_ticks(ax, self._get_index_name(), str_index, s_edge, e_edge)
 
     def _decorate_ticks(self, ax: Axes, name, ticklabels, start_edge, end_edge):
         ax.set_xlim((start_edge, end_edge))
@@ -1608,13 +1612,17 @@ def _plot(  # type: ignore[override]
     ):
         return ax.barh(x, y, w, left=start, log=log, **kwds)
 
+    def _get_custom_index_name(self):
+        return self.ylabel
+
     def _decorate_ticks(self, ax: Axes, name, ticklabels, start_edge, end_edge):
         # horizontal bars
         ax.set_ylim((start_edge, end_edge))
         ax.set_yticks(self.tick_pos)
         ax.set_yticklabels(ticklabels)
         if name is not None and self.use_index:
             ax.set_ylabel(name)
+        ax.set_xlabel(self.xlabel)
 
 
 class PiePlot(MPLPlot):

pandas/tests/plotting/test_series.py

@@ -787,16 +787,20 @@ def test_style_single_ok(self):
         "index_name, old_label, new_label",
         [(None, "", "new"), ("old", "old", "new"), (None, "", "")],
     )
-    @pytest.mark.parametrize("kind", ["line", "area", "bar"])
+    @pytest.mark.parametrize("kind", ["line", "area", "bar", "barh"])
     def test_xlabel_ylabel_series(self, kind, index_name, old_label, new_label):
         # GH 9093
         ser = Series([1, 2, 3, 4])
         ser.index.name = index_name
 
-        # default is the ylabel is not shown and xlabel is index name
+        # default is the ylabel is not shown and xlabel is index name (reverse for barh)
         ax = ser.plot(kind=kind)
-        assert ax.get_ylabel() == ""
-        assert ax.get_xlabel() == old_label
+        if kind == "barh":
+            assert ax.get_xlabel() == ""
+            assert ax.get_ylabel() == old_label
+        else:
+            assert ax.get_ylabel() == ""
+            assert ax.get_xlabel() == old_label
 
         # old xlabel will be overridden and assigned ylabel will be used as ylabel
         ax = ser.plot(kind=kind, ylabel=new_label, xlabel=new_label)