BUG: Fix for xlabel/ylabel in barh plot

doc/source/whatsnew/v1.4.0.rst

@@ -884,6 +884,7 @@ Period
 Plotting
 ^^^^^^^^
 - When given non-numeric data, :meth:`DataFrame.boxplot` now raises a ``ValueError`` rather than a cryptic ``KeyError`` or ``ZeroDivisionError``, in line with other plotting functions like :meth:`DataFrame.hist`. (:issue:`43480`)
+- 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

@@ -767,8 +767,10 @@ def _get_index_name(self) -> str | None:
                 name = pprint_thing(name)
 
         # GH 9093, override the default xlabel if xlabel is provided.
-        if self.xlabel is not None:
+        if self.xlabel is not None and self.orientation == "vertical":
             name = pprint_thing(self.xlabel)
+        if self.ylabel is not None and self.orientation == "horizontal":
+            name = pprint_thing(self.ylabel)
 
         return name
 
@@ -1567,17 +1569,19 @@ def _make_plot(self):
                 )
             self._append_legend_handles_labels(rect, label)
 
+    def _get_bar_index_name(self):
+        return self.xlabel or self._get_index_name()
+
     def _post_plot_logic(self, ax: Axes, data):
         if self.use_index:
             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_bar_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_bar_index_name(self):
+        return self.ylabel or self._get_index_name()
+
     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)