Deprecate unused, untested Affine2D.identity().

anntzer · anntzer · commit bd549f95596f · 2022-02-18T08:53:38.000+01:00
`Affine2D()` is exactly identical (it's the implementation...), shorter
to type, and we have clearly standardized on using that; removing
identity() also avoids any possible confusion with IdentityTransform
(see also the removed docstring).
diff --git a/doc/api/next_api_changes/deprecations/22490-AL.rst b/doc/api/next_api_changes/deprecations/22490-AL.rst
@@ -0,0 +1,4 @@
+``Affine2D.indentity()``
+~~~~~~~~~~~~~~~~~~~~~~~~
+... is deprecated in favor of directly calling the `.Affine2D` constructor with
+no arguments.
diff --git a/lib/matplotlib/transforms.py b/lib/matplotlib/transforms.py
@@ -1957,6 +1957,7 @@ def set(self, other):
         self._mtx = other.get_matrix()
         self.invalidate()
 
+    @_api.deprecated("3.6", alternative="Affine2D()")
     @staticmethod
     def identity():
         """
