Sharey keyword for boxplot

doc/source/whatsnew/v0.23.1.txt

@@ -76,7 +76,7 @@ I/O
 Plotting
 ^^^^^^^^
 
--
+- Optional sharing of x/y-axis by pandas.DataFrame().groupby().boxplot() (:issue: `20968`)
 -
 
 Reshaping

pandas/plotting/_core.py

@@ -2548,7 +2548,7 @@ def plot_group(group, ax):
 
 def boxplot_frame_groupby(grouped, subplots=True, column=None, fontsize=None,
                           rot=0, grid=True, ax=None, figsize=None,
-                          layout=None, **kwds):
+                          layout=None, sharex=False, sharey=True, **kwds):
     """
     Make box plots from DataFrameGroupBy data.
 
@@ -2567,6 +2567,14 @@ def boxplot_frame_groupby(grouped, subplots=True, column=None, fontsize=None,
     figsize : A tuple (width, height) in inches
     layout : tuple (optional)
         (rows, columns) for the layout of the plot
+    sharex : bool, default False
+        Whether x-axes will be shared among subplots
+
+        .. versionadded:: 0.23.1
+    sharey : bool, default True
+        Whether y-axes will be shared among subplots
+
+        .. versionadded:: 0.23.1
     `**kwds` : Keyword Arguments
         All other plotting keyword arguments to be passed to
         matplotlib's boxplot function
@@ -2598,7 +2606,7 @@ def boxplot_frame_groupby(grouped, subplots=True, column=None, fontsize=None,
     if subplots is True:
         naxes = len(grouped)
         fig, axes = _subplots(naxes=naxes, squeeze=False,
-                              ax=ax, sharex=False, sharey=True,
+                              ax=ax, sharex=sharex, sharey=sharey,
                               figsize=figsize, layout=layout)
         axes = _flatten(axes)
 

pandas/tests/plotting/test_frame.py

@@ -367,6 +367,57 @@ def test_subplots(self):
             for ax in axes:
                 assert ax.get_legend() is None
 
+    def test_groupby_boxplot_sharey(self):
+        # https://github.com/pandas-dev/pandas/issues/20968
+        # sharey can now be switched check whether the right
+        # pair of axes is turned on or off
+
+        df = DataFrame({'a': [-1.43, -0.15, -3.70, -1.43, -0.14],
+                        'b': [0.56, 0.84, 0.29, 0.56, 0.85],
+                        'c': [0, 1, 2, 3, 1]},
+                       index=[0, 1, 2, 3, 4])
+
+        # behavior without keyword
+        axes = df.groupby('c').boxplot()
+        expected = [True, False, True, False]
+        self._assert_ytickslabels_visibility(axes, expected)
+
+        # set sharey=True should be identical
+        axes = df.groupby('c').boxplot(sharey=True)
+        expected = [True, False, True, False]
+        self._assert_ytickslabels_visibility(axes, expected)
+
+        # sharey=False, all yticklabels should be visible
+        axes = df.groupby('c').boxplot(sharey=False)
+        expected = [True, True, True, True]
+        self._assert_ytickslabels_visibility(axes, expected)
+
+    def test_groupby_boxplot_sharex(self):
+        # https://github.com/pandas-dev/pandas/issues/20968
+        # sharex can now be switched check whether the right
+        # pair of axes is turned on or off
+
+        df = DataFrame({'a': [-1.43, -0.15, -3.70, -1.43, -0.14],
+                        'b': [0.56, 0.84, 0.29, 0.56, 0.85],
+                        'c': [0, 1, 2, 3, 1]},
+                       index=[0, 1, 2, 3, 4])
+
+        # behavior without keyword
+        axes = df.groupby('c').boxplot()
+        expected = [True, True, True, True]
+        self._assert_xtickslabels_visibility(axes, expected)
+
+        # set sharex=False should be identical
+        axes = df.groupby('c').boxplot(sharex=False)
+        expected = [True, True, True, True]
+        self._assert_xtickslabels_visibility(axes, expected)
+
+        # sharex=True, yticklabels should be visible
+        # only for bottom plots
+        axes = df.groupby('c').boxplot(sharex=True)
+        expected = [False, False, True, True]
+        self._assert_xtickslabels_visibility(axes, expected)
+
     @pytest.mark.slow
     def test_subplots_timeseries(self):
         idx = date_range(start='2014-07-01', freq='M', periods=10)
@@ -2921,6 +2972,14 @@ def test_secondary_axis_font_size(self, method):
         self._check_ticks_props(axes=ax.right_ax,
                                 ylabelsize=fontsize)
 
+    def _assert_ytickslabels_visibility(self, axes, expected):
+        for ax, exp in zip(axes, expected):
+            self._check_visible(ax.get_yticklabels(), visible=exp)
+
+    def _assert_xtickslabels_visibility(self, axes, expected):
+        for ax, exp in zip(axes, expected):
+            self._check_visible(ax.get_xticklabels(), visible=exp)
+
 
 def _generate_4_axes_via_gridspec():
     import matplotlib.pyplot as plt