matplotlib · dikshajangra12918-oss · Apr 21, 2026 · Apr 21, 2026 · Apr 22, 2026 · Apr 22, 2026
diff --git a/lib/matplotlib/scale.py b/lib/matplotlib/scale.py
@@ -956,6 +956,21 @@ def register_scale(scale_class):
         )
 
 
+def deregister_scale(name):
+    """
+    Remove a custom scale from the registry.
+
+    Parameters
+    ----------
+    name : str
+        The name of the scale to remove.
+    """
+    if name not in _scale_mapping:
+        raise ValueError(f"Scale '{name}' is not registered.")
+    _scale_mapping.pop(name)
+    _scale_has_axis_parameter.pop(name, None)
+
+
 def _get_scale_docs():
     """
     Helper function for generating docstrings related to scales.

diff --git a/lib/matplotlib/scale.pyi b/lib/matplotlib/scale.pyi
@@ -182,4 +182,5 @@ class LogitScale(ScaleBase):
 def get_scale_names() -> list[str]: ...
 def scale_factory(scale: str, axis: Axis, **kwargs) -> ScaleBase: ...
 def register_scale(scale_class: type[ScaleBase]) -> None: ...
+def deregister_scale(name: str) -> None: ...
 def _make_axis_parameter_optional(init_func: Callable[..., None]) -> Callable[..., None]: ...
diff --git a/lib/matplotlib/tests/test_scale.py b/lib/matplotlib/tests/test_scale.py
@@ -330,9 +330,7 @@ def set_default_locators_and_formatters(self, axis):
         ax.set_xscale('custom')
         assert isinstance(ax.xaxis.get_transform(), CustomTransform)
     finally:
-        # cleanup - there's no public unregister_scale()
-        del mscale._scale_mapping["custom"]
-        del mscale._scale_has_axis_parameter["custom"]
+        mscale.deregister_scale("custom")
 
 
 def test_custom_scale_with_axis():
@@ -368,9 +366,7 @@ def set_default_locators_and_formatters(self, axis):
         ax.set_xscale('custom')
         assert isinstance(ax.xaxis.get_transform(), CustomTransform)
     finally:
-        # cleanup - there's no public unregister_scale()
-        del mscale._scale_mapping["custom"]
-        del mscale._scale_has_axis_parameter["custom"]
+        mscale.deregister_scale("custom")
 
 
 def test_val_in_range():
@@ -433,3 +429,34 @@ def test_val_in_range_base_fallback():
     assert s.val_in_range(np.nan) is False
     assert s.val_in_range(np.inf) is False
     assert s.val_in_range(-np.inf) is False
+
+
+def test_deregister_scale():
+    """Test that deregister_scale removes a scale correctly."""
+    # Register a temporary custom scale
+    class TempScale(mscale.ScaleBase):
+        name = 'temp_test_scale'
+
+        def __init__(self):
+            pass
+
+        def get_transform(self):
+                from matplotlib.transforms import IdentityTransform
+                return IdentityTransform()
+
+        def set_default_locators_and_formatters(
+                self, axis):
+            pass
+
+    mscale.register_scale(TempScale)
+    assert 'temp_test_scale' in mscale._scale_mapping
+
+    # Now unregister it
+    mscale.deregister_scale('temp_test_scale')
+    assert 'temp_test_scale' not in mscale._scale_mapping
+
+
+def test_deregister_scale_invalid():
+    """Test that deregister_scale raises ValueError for unknown scale."""
+    with pytest.raises(ValueError, match="not registered"):
+        mscale.deregister_scale('this_does_not_exist')