From 51c0403fea0dd41b42df20f903c0adad083c8ac5 Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Tue, 7 Nov 2023 18:41:40 -0800
Subject: [PATCH 1/3] REF: make plotting less stateful

---
 pandas/plotting/_matplotlib/core.py | 30 ++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/pandas/plotting/_matplotlib/core.py b/pandas/plotting/_matplotlib/core.py
index b67a8186c8c2b..a4232da25bf37 100644
--- a/pandas/plotting/_matplotlib/core.py
+++ b/pandas/plotting/_matplotlib/core.py
@@ -126,8 +126,6 @@ def _kind(self) -> str:
     def orientation(self) -> str | None:
         return None
 
-    axes: np.ndarray  # of Axes objects
-
     def __init__(
         self,
         data,
@@ -236,10 +234,11 @@ def __init__(
         self.mark_right = kwds.pop("mark_right", True)
         self.stacked = kwds.pop("stacked", False)
 
+        # ax may be an Axes object or (if self.subplots) an ndarray of
+        #  Axes objects
         self.ax = ax
         # TODO: deprecate fig keyword as it is ignored, not passed in tests
         #  as of 2023-11-05
-        self.axes = np.array([], dtype=object)  # "real" version get set in `generate`
 
         # parse errorbar input if given
         xerr = kwds.pop("xerr", None)
@@ -463,7 +462,7 @@ def draw(self) -> None:
     @final
     def generate(self) -> None:
         self._compute_plot_data()
-        fig = self._setup_subplots()
+        fig = self.fig
         self._make_plot(fig)
         self._add_table()
         self._make_legend()
@@ -509,7 +508,19 @@ def _maybe_right_yaxis(self, ax: Axes, axes_num: int):
             return new_ax
 
     @final
-    def _setup_subplots(self) -> Figure:
+    @cache_readonly
+    def fig(self) -> Figure:
+        return self._axes_and_fig[1]
+
+    @final
+    @cache_readonly
+    # TODO: can we annotate this as both a Sequence[Axes] and ndarray[object]?
+    def axes(self) -> Sequence[Axes]:
+        return self._axes_and_fig[0]
+
+    @final
+    @cache_readonly
+    def _axes_and_fig(self) -> tuple[Sequence[Axes], Figure]:
         if self.subplots:
             naxes = (
                 self.nseries if isinstance(self.subplots, bool) else len(self.subplots)
@@ -552,8 +563,7 @@ def _setup_subplots(self) -> Figure:
         elif self.logy == "sym" or self.loglog == "sym":
             [a.set_yscale("symlog") for a in axes]
 
-        self.axes = axes
-        return fig
+        return axes, fig
 
     @property
     def result(self):
@@ -562,7 +572,8 @@ def result(self):
         """
         if self.subplots:
             if self.layout is not None and not is_list_like(self.ax):
-                return self.axes.reshape(*self.layout)
+                # error: "Sequence[Any]" has no attribute "reshape"
+                return self.axes.reshape(*self.layout)  # type: ignore[attr-defined]
             else:
                 return self.axes
         else:
@@ -972,7 +983,8 @@ def _get_ax(self, i: int):
             i = self._col_idx_to_axis_idx(i)
             ax = self.axes[i]
             ax = self._maybe_right_yaxis(ax, i)
-            self.axes[i] = ax
+            # error: Unsupported target for indexed assignment ("Sequence[Any]")
+            self.axes[i] = ax  # type: ignore[index]
         else:
             ax = self.axes[0]
             ax = self._maybe_right_yaxis(ax, i)

From f449fb2320a462aca3125366c8af396da629f674 Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Wed, 8 Nov 2023 15:50:19 -0800
Subject: [PATCH 2/3] mypy fixup

---
 pandas/plotting/_matplotlib/core.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pandas/plotting/_matplotlib/core.py b/pandas/plotting/_matplotlib/core.py
index a4232da25bf37..4f12a2def2931 100644
--- a/pandas/plotting/_matplotlib/core.py
+++ b/pandas/plotting/_matplotlib/core.py
@@ -13,11 +13,13 @@
     TYPE_CHECKING,
     Any,
     Literal,
+    cast,
     final,
 )
 import warnings
 
 import matplotlib as mpl
+from matplotlib.axes import Axes
 import numpy as np
 
 from pandas.errors import AbstractMethodError
@@ -81,7 +83,6 @@
 
 if TYPE_CHECKING:
     from matplotlib.artist import Artist
-    from matplotlib.axes import Axes
     from matplotlib.axis import Axis
     from matplotlib.figure import Figure
 
@@ -563,7 +564,8 @@ def _axes_and_fig(self) -> tuple[Sequence[Axes], Figure]:
         elif self.logy == "sym" or self.loglog == "sym":
             [a.set_yscale("symlog") for a in axes]
 
-        return axes, fig
+        axes_seq = cast(Sequence[Axes], axes)
+        return axes_seq, fig
 
     @property
     def result(self):

From b0c1d0873ed89f72f5efbf40fdf97b653069430d Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Wed, 8 Nov 2023 19:17:19 -0800
Subject: [PATCH 3/3] Fix registry test

---
 pandas/plotting/_matplotlib/core.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/plotting/_matplotlib/core.py b/pandas/plotting/_matplotlib/core.py
index 4f12a2def2931..848c6d45c494d 100644
--- a/pandas/plotting/_matplotlib/core.py
+++ b/pandas/plotting/_matplotlib/core.py
@@ -19,7 +19,6 @@
 import warnings
 
 import matplotlib as mpl
-from matplotlib.axes import Axes
 import numpy as np
 
 from pandas.errors import AbstractMethodError
@@ -83,6 +82,7 @@
 
 if TYPE_CHECKING:
     from matplotlib.artist import Artist
+    from matplotlib.axes import Axes
     from matplotlib.axis import Axis
     from matplotlib.figure import Figure
 
@@ -564,7 +564,7 @@ def _axes_and_fig(self) -> tuple[Sequence[Axes], Figure]:
         elif self.logy == "sym" or self.loglog == "sym":
             [a.set_yscale("symlog") for a in axes]
 
-        axes_seq = cast(Sequence[Axes], axes)
+        axes_seq = cast(Sequence["Axes"], axes)
         return axes_seq, fig
 
     @property