matplotlib · tacaswell · Dec 4, 2022 · Dec 4, 2022
diff --git a/lib/matplotlib/artist.py b/lib/matplotlib/artist.py
@@ -19,6 +19,9 @@
 
 _log = logging.getLogger(__name__)
 
+# a tombstone sentinel to ensure we never reset the axes or figure on an Artist
+_tombstone = object()
+
 
 def _prevent_rasterization(draw):
     # We assume that by default artists are not allowed to rasterize (unless
@@ -264,7 +267,7 @@ def remove(self):
             if (fig := self.get_figure(root=False)) is not None:
                 if not _ax_flag:
                     fig.stale = True
-                self._parent_figure = None
+                self._parent_figure = _tombstone
 
         else:
             raise NotImplementedError('cannot remove artist')
@@ -301,18 +304,35 @@ def convert_yunits(self, y):
     @property
     def axes(self):
         """The `~.axes.Axes` instance the artist resides in, or *None*."""
-        return self._axes
+        return self._axes if self._axes is not _tombstone else None
 
     @axes.setter
     def axes(self, new_axes):
         if (new_axes is not None and self._axes is not None
                 and new_axes != self._axes):
-            raise ValueError("Can not reset the Axes. You are probably trying to reuse "
-                             "an artist in more than one Axes which is not supported")
+            if self._axes is _tombstone:
+                extra = (
+                    f"The artist {self!r} has had its Axes reset to None " +
+                    "but was previously included in one."
+                )
+            else:
+                extra = (
+                    f"The artist {self!r} is currently in {self._axes!r} " +
+                    f"in the figure {self._axes.figure!r}."
+                )
+            raise RuntimeError(
+                "Can not reset the Axes.  You are probably " +
+                "trying to reuse an artist in more than one " +
+                "Axes which is not supported.  " +
+                extra
+            )
+        if self._axes is not None and new_axes is None:
+            new_axes = _tombstone
         self._axes = new_axes
         if new_axes is not None and new_axes is not self:
             self.stale_callback = _stale_axes_callback
 
+
     @property
     def stale(self):
         """
@@ -759,6 +779,9 @@ def get_figure(self, root=False):
             If False, return the (Sub)Figure this artist is on.  If True,
             return the root Figure for a nested tree of SubFigures.
         """
+        if self._parent_figure is _tombstone:
+            return None
+
         if root and self._parent_figure is not None:
             return self._parent_figure.get_figure(root=True)
 
@@ -794,8 +817,24 @@ def set_figure(self, fig):
         # is not allowed for the same reason as adding the same instance
         # to more than one Axes
         if self._parent_figure is not None:
-            raise RuntimeError("Can not put single artist in "
-                               "more than one figure")
+            if fig is None:
+                self._parent_figure = _tombstone
+                return
+            if self._parent_figure is _tombstone:
+                extra = (
+                    f"The artist {self!r} has had its Figure reset to None " +
+                    "but was previously included in one."
+                )
+            else:
+                extra = (
+                    f"The artist {self!r} is currently in {self._parent_figure!r}."
+                )
+            raise RuntimeError(
+                "Can not reset the figure.  You are probably " +
+                "trying to reuse an artist in more than one " +
+                "Figure which is not supported.  " +
+                extra
+            )
         self._parent_figure = fig
         if self._parent_figure and self._parent_figure is not self:
             self.pchanged()

diff --git a/lib/matplotlib/tests/test_artist.py b/lib/matplotlib/tests/test_artist.py
@@ -623,3 +623,37 @@ def test_get_figure():
     assert ax.figure is sfig2
     assert fig.figure is fig
     assert sfig2.figure is fig
+
+
+def test_no_reset():
+    fig, (ax1, ax2) = plt.subplots(2)
+    fig2 = plt.figure()
+    ln, = ax1.plot(range(5))
+    with pytest.raises(
+            RuntimeError, match=f"The artist {ln!r} is currently in {ax1!r}"
+    ):
+        ax2.add_line(ln)
+    with pytest.raises(
+            RuntimeError, match=f"The artist {ln!r} is currently in {ax1!r}"
+    ):
+        ln.axes = ax2
+    with pytest.raises(
+            RuntimeError, match=f"The artist {ln!r} is currently in {fig!r}"
+    ):
+        ln.figure = fig2
+
+    ln.remove()
+    assert ln.figure is None
+    assert ln.axes is None
+    with pytest.raises(
+            RuntimeError, match=f"The artist {ln!r} has had its Figure reset "
+    ):
+        ax2.add_line(ln)
+
+    with pytest.raises(
+            RuntimeError, match=f"The artist {ln!r} has had its Axes reset "
+    ):
+        ln.axes = ax2
+
+    assert ln.axes is None
+    assert ln.figure is None
diff --git a/lib/matplotlib/tests/test_offsetbox.py b/lib/matplotlib/tests/test_offsetbox.py
@@ -103,8 +103,9 @@ def test_offsetbox_loc_codes():
              'center': 10,
              }
     fig, ax = plt.subplots()
-    da = DrawingArea(100, 100)
+
     for code in codes:
+        da = DrawingArea(100, 100)
         anchored_box = AnchoredOffsetbox(loc=code, child=da)
         ax.add_artist(anchored_box)
     fig.canvas.draw()