CoW: Clean up some copy usage (pandas-dev#57513)

pandas/core/computation/eval.py

@@ -378,7 +378,7 @@ def eval(
                 try:
                     target = env.target
                     if isinstance(target, NDFrame):
-                        target = target.copy(deep=None)
+                        target = target.copy(deep=False)
                     else:
                         target = target.copy()
                 except AttributeError as err:

pandas/core/generic.py

@@ -7488,7 +7488,7 @@ def replace(
             if not self.size:
                 if inplace:
                     return None
-                return self.copy(deep=None)
+                return self.copy(deep=False)
 
             if is_dict_like(to_replace):
                 if is_dict_like(value):  # {'A' : NA} -> {'A' : 0}
@@ -10279,7 +10279,7 @@ def shift(
             fill_value = lib.no_default
 
         if periods == 0:
-            return self.copy(deep=None)
+            return self.copy(deep=False)
 
         if is_list_like(periods) and isinstance(self, ABCSeries):
             return self.to_frame().shift(

pandas/core/internals/managers.py

@@ -702,7 +702,7 @@ def _combine(self, blocks: list[Block], index: Index | None = None) -> Self:
     def nblocks(self) -> int:
         return len(self.blocks)
 
-    def copy(self, deep: bool | None | Literal["all"] = True) -> Self:
+    def copy(self, deep: bool | Literal["all"] = True) -> Self:
         """
         Make deep or shallow copy of BlockManager
 
@@ -716,7 +716,6 @@ def copy(self, deep: bool | None | Literal["all"] = True) -> Self:
         -------
         BlockManager
         """
-        deep = deep if deep is not None else False
         # this preserves the notion of view copying of axes
         if deep:
             # hit in e.g. tests.io.json.test_pandas

pandas/tests/copy_view/test_internals.py

@@ -70,7 +70,7 @@ def test_iset_splits_blocks_inplace(locs, arr, dtype):
     )
     arr = arr.astype(dtype)
     df_orig = df.copy()
-    df2 = df.copy(deep=None)  # Trigger a CoW (if enabled, otherwise makes copy)
+    df2 = df.copy(deep=False)  # Trigger a CoW (if enabled, otherwise makes copy)
     df2._mgr.iset(locs, arr, inplace=True)
 
     tm.assert_frame_equal(df, df_orig)

pandas/tests/copy_view/test_methods.py

@@ -1243,7 +1243,7 @@ def test_interpolate_creates_copy():
 def test_isetitem():
     df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6], "c": [7, 8, 9]})
     df_orig = df.copy()
-    df2 = df.copy(deep=None)  # Trigger a CoW
+    df2 = df.copy(deep=False)  # Trigger a CoW
     df2.isetitem(1, np.array([-1, -2, -3]))  # This is inplace
     assert np.shares_memory(get_array(df, "c"), get_array(df2, "c"))
     assert np.shares_memory(get_array(df, "a"), get_array(df2, "a"))