BUG: Fix .hist and .plot.hist when passing existing figure (#37278)

Author: krsnik93

doc/source/whatsnew/v1.2.0.rst

@@ -476,6 +476,7 @@ Plotting
 
 - Bug in :meth:`DataFrame.plot` was rotating xticklabels when ``subplots=True``, even if the x-axis wasn't an irregular time series (:issue:`29460`)
 - Bug in :meth:`DataFrame.plot` where a marker letter in the ``style`` keyword sometimes causes a ``ValueError`` (:issue:`21003`)
+- Bug in :meth:`DataFrame.hist`, :meth:`DataFrame.plot.hist` and :meth:`Series.plot.hist` when passing an existing figure (:issue:`37278`)
 - Twinned axes were losing their tick labels which should only happen to all but the last row or column of 'externally' shared axes (:issue:`33819`)
 
 Groupby/resample/rolling

pandas/plotting/_core.py

@@ -12,6 +12,8 @@
 from pandas.core.base import PandasObject
 
 if TYPE_CHECKING:
+    from matplotlib.figure import Figure
+
     from pandas import DataFrame
 
 
@@ -107,6 +109,7 @@ def hist_frame(
     xrot: Optional[float] = None,
     ylabelsize: Optional[int] = None,
     yrot: Optional[float] = None,
+    figure: Optional["Figure"] = None,
     ax=None,
     sharex: bool = False,
     sharey: bool = False,
@@ -146,6 +149,8 @@ def hist_frame(
     yrot : float, default None
         Rotation of y axis labels. For example, a value of 90 displays the
         y labels rotated 90 degrees clockwise.
+    figure : Matplotlib Figure object, default None
+        The figure to plot the histogram on.
     ax : Matplotlib axes object, default None
         The axes to plot the histogram on.
     sharex : bool, default True if ax is None else False
@@ -217,6 +222,7 @@ def hist_frame(
         xrot=xrot,
         ylabelsize=ylabelsize,
         yrot=yrot,
+        figure=figure,
         ax=ax,
         sharex=sharex,
         sharey=sharey,

pandas/plotting/_matplotlib/__init__.py

@@ -51,6 +51,10 @@ def plot(data, kind, **kwargs):
     # work)
     import matplotlib.pyplot as plt
 
+    if kwargs.get("figure"):
+        kwargs["fig"] = kwargs.get("figure")
+        kwargs["ax"] = kwargs["figure"].gca()
+        kwargs.pop("reuse_plot", None)
     if kwargs.pop("reuse_plot", False):
         ax = kwargs.get("ax")
         if ax is None and len(plt.get_fignums()) > 0:

pandas/plotting/_matplotlib/core.py

@@ -325,12 +325,16 @@ def _setup_subplots(self):
                 sharex=self.sharex,
                 sharey=self.sharey,
                 figsize=self.figsize,
+                figure=self.fig,
                 ax=self.ax,
                 layout=self.layout,
                 layout_type=self._layout_type,
             )
         else:
-            if self.ax is None:
+            if self.fig is not None:
+                fig = self.fig
+                axes = fig.add_subplot(111)
+            elif self.ax is None:
                 fig = self.plt.figure(figsize=self.figsize)
                 axes = fig.add_subplot(111)
             else:

pandas/plotting/_matplotlib/hist.py

@@ -1,4 +1,4 @@
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 import numpy as np
 
@@ -16,6 +16,7 @@
 
 if TYPE_CHECKING:
     from matplotlib.axes import Axes
+    from matplotlib.figure import Figure
 
 
 class HistPlot(LinePlot):
@@ -181,6 +182,7 @@ def _grouped_plot(
     column=None,
     by=None,
     numeric_only=True,
+    figure: Optional["Figure"] = None,
     figsize=None,
     sharex=True,
     sharey=True,
@@ -203,7 +205,13 @@ def _grouped_plot(
 
     naxes = len(grouped)
     fig, axes = create_subplots(
-        naxes=naxes, figsize=figsize, sharex=sharex, sharey=sharey, ax=ax, layout=layout
+        naxes=naxes,
+        figure=figure,
+        figsize=figsize,
+        sharex=sharex,
+        sharey=sharey,
+        ax=ax,
+        layout=layout,
     )
 
     _axes = flatten_axes(axes)
@@ -222,6 +230,7 @@ def _grouped_hist(
     data,
     column=None,
     by=None,
+    figure=None,
     ax=None,
     bins=50,
     figsize=None,
@@ -245,6 +254,7 @@ def _grouped_hist(
     data : Series/DataFrame
     column : object, optional
     by : object, optional
+    figure: figure, optional
     ax : axes, optional
     bins : int, default 50
     figsize : tuple, optional
@@ -282,6 +292,7 @@ def plot_group(group, ax):
         data,
         column=column,
         by=by,
+        figure=figure,
         sharex=sharex,
         sharey=sharey,
         ax=ax,
@@ -381,6 +392,7 @@ def hist_frame(
     xrot=None,
     ylabelsize=None,
     yrot=None,
+    figure=None,
     ax=None,
     sharex=False,
     sharey=False,
@@ -397,6 +409,7 @@ def hist_frame(
             data,
             column=column,
             by=by,
+            figure=figure,
             ax=ax,
             grid=grid,
             figsize=figsize,
@@ -430,6 +443,7 @@ def hist_frame(
 
     fig, axes = create_subplots(
         naxes=naxes,
+        figure=figure,
         ax=ax,
         squeeze=False,
         sharex=sharex,

pandas/plotting/_matplotlib/tools.py

@@ -1,6 +1,6 @@
 # being a bit too dynamic
 from math import ceil
-from typing import TYPE_CHECKING, Iterable, List, Sequence, Tuple, Union
+from typing import TYPE_CHECKING, Iterable, List, Optional, Sequence, Tuple, Union
 import warnings
 
 import matplotlib.table
@@ -17,6 +17,7 @@
 if TYPE_CHECKING:
     from matplotlib.axes import Axes
     from matplotlib.axis import Axis
+    from matplotlib.figure import Figure
     from matplotlib.lines import Line2D
     from matplotlib.table import Table
 
@@ -106,6 +107,7 @@ def create_subplots(
     sharey: bool = False,
     squeeze: bool = True,
     subplot_kw=None,
+    figure: Optional["Figure"] = None,
     ax=None,
     layout=None,
     layout_type: str = "box",
@@ -145,6 +147,9 @@ def create_subplots(
       Dict with keywords passed to the add_subplot() call used to create each
       subplots.
 
+    figure : Matplotlib figure object, optional
+        Existing figure to be used for plotting.
+
     ax : Matplotlib axis object, optional
 
     layout : tuple
@@ -190,7 +195,9 @@ def create_subplots(
     if subplot_kw is None:
         subplot_kw = {}
 
-    if ax is None:
+    if figure is not None:
+        fig = figure
+    elif ax is None:
         fig = plt.figure(**fig_kw)
     else:
         if is_list_like(ax):

pandas/tests/plotting/test_hist_method.py

@@ -1,5 +1,6 @@
 """ Test cases for .hist method """
 
+import matplotlib.pyplot as plt
 import numpy as np
 from numpy.random import randn
 import pytest
@@ -152,6 +153,13 @@ def test_hist_with_legend_raises(self, by):
         with pytest.raises(ValueError, match="Cannot use both legend and label"):
             s.hist(legend=True, by=by, label="c")
 
+    def test_hist_with_passed_figure(self):
+        # GH37278
+        index = 15 * ["1"] + 15 * ["2"]
+        s = Series(np.random.randn(30), index=index, name="a")
+        _check_plot_works(s.hist, figure=plt.figure())
+        _check_plot_works(s.plot.hist, figure=plt.figure())
+
 
 @td.skip_if_no_mpl
 class TestDataFramePlots(TestPlotBase):
@@ -395,6 +403,13 @@ def test_hist_with_legend_raises(self, by, column):
         with pytest.raises(ValueError, match="Cannot use both legend and label"):
             df.hist(legend=True, by=by, column=column, label="d")
 
+    def test_hist_with_passed_figure(self):
+        # GH37278
+        index = Index(15 * ["1"] + 15 * ["2"], name="c")
+        df = DataFrame(np.random.randn(30, 2), index=index, columns=["a", "b"])
+        _check_plot_works(df.hist, figure=plt.figure())
+        _check_plot_works(df.plot.hist, figure=plt.figure())
+
 
 @td.skip_if_no_mpl
 class TestDataFrameGroupByPlots(TestPlotBase):