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Merged
merged 12 commits into from
Jan 21, 2023
Merged

TST: test explicit copy keyword with CoW enabled #50536

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4f4f663
TST: test explicit copy keyword with CoW enabled
jorisvandenbossche Jan 3, 2023
e4623f5
fixup test
jorisvandenbossche Jan 4, 2023
5cbfc29
Merge remote-tracking branch 'upstream/main' into cow-copy-keyword
jorisvandenbossche Jan 4, 2023
3cc360a
undo previous changes
jorisvandenbossche Jan 13, 2023
2fa9007
Merge remote-tracking branch 'upstream/main' into cow-copy-keyword
jorisvandenbossche Jan 13, 2023
ac7a222
single parametrized test
jorisvandenbossche Jan 13, 2023
dd458f7
fix rebase
jorisvandenbossche Jan 13, 2023
12a41d3
add more methods
jorisvandenbossche Jan 16, 2023
7ece5fd
add time related methods
jorisvandenbossche Jan 16, 2023
3ec49a4
add set_flags
jorisvandenbossche Jan 16, 2023
3c8a785
Merge remote-tracking branch 'upstream/main' into cow-copy-keyword
jorisvandenbossche Jan 20, 2023
e679998
add swapaxes
jorisvandenbossche Jan 20, 2023
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76 changes: 52 additions & 24 deletions pandas/tests/copy_view/test_methods.py
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Original file line number Diff line number Diff line change
Expand Up @@ -77,22 +77,31 @@ def test_reset_index(using_copy_on_write):
tm.assert_frame_equal(df, df_orig)


def test_rename_columns(using_copy_on_write):
@pytest.mark.parametrize("copy", [True, None, False])
def test_rename_columns(using_copy_on_write, copy):
# Case: renaming columns returns a new dataframe
# + afterwards modifying the result
df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6], "c": [0.1, 0.2, 0.3]})
df_orig = df.copy()
df2 = df.rename(columns=str.upper)
df2 = df.rename(columns=str.upper, copy=copy)

if using_copy_on_write:
if (using_copy_on_write and copy is not True) or copy is False:
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The current PR experiments with combining testing the copy=True/False/None keyword in those tests that we have been adding to test the CoW behaviour of those methods.

Combining it would give the least duplication, but, I have to say that the if expressions are getting quite complicated and hard to follow ..
For example here if (using_copy_on_write and copy is not True) or copy is False and below if using_copy_on_write or copy is not False and if using_copy_on_write and copy is not True, all slightly different.

assert np.shares_memory(get_array(df2, "A"), get_array(df, "a"))
else:
assert not np.shares_memory(get_array(df2, "A"), get_array(df, "a"))
df2.iloc[0, 0] = 0
assert not np.shares_memory(get_array(df2, "A"), get_array(df, "a"))
if using_copy_on_write:
if using_copy_on_write or copy is not False:
assert not np.shares_memory(get_array(df2, "A"), get_array(df, "a"))
else:
assert np.shares_memory(get_array(df2, "A"), get_array(df, "a"))
if using_copy_on_write and copy is not True:
assert np.shares_memory(get_array(df2, "C"), get_array(df, "c"))
expected = DataFrame({"A": [0, 2, 3], "B": [4, 5, 6], "C": [0.1, 0.2, 0.3]})
tm.assert_frame_equal(df2, expected)
tm.assert_frame_equal(df, df_orig)
if using_copy_on_write or copy is not False:
tm.assert_frame_equal(df, df_orig)
else:
assert not df.equals(df_orig)


def test_rename_columns_modify_parent(using_copy_on_write):
Expand All @@ -115,24 +124,32 @@ def test_rename_columns_modify_parent(using_copy_on_write):
tm.assert_frame_equal(df2, df2_orig)


def test_reindex_columns(using_copy_on_write):
@pytest.mark.parametrize("copy", [True, None, False])
def test_reindex_columns(using_copy_on_write, using_array_manager, copy):
# Case: reindexing the column returns a new dataframe
# + afterwards modifying the result
df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6], "c": [0.1, 0.2, 0.3]})
df_orig = df.copy()
df2 = df.reindex(columns=["a", "c"])
df2 = df.reindex(columns=["a", "c"], copy=copy)

if using_copy_on_write:
# TODO copy=False without CoW still returns a copy in this case
# TODO copy=True with CoW or AM still returns a view
# ((using_COW or using_AM) and copy is not True) or copy is False:
if using_copy_on_write or using_array_manager:
# still shares memory (df2 is a shallow copy)
assert np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
else:
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
# mutating df2 triggers a copy-on-write for that column
df2.iloc[0, 0] = 0
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
if using_copy_on_write:
assert np.shares_memory(get_array(df2, "c"), get_array(df, "c"))
tm.assert_frame_equal(df, df_orig)
if using_array_manager:
assert np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
assert df.iloc[0, 0] == 0
else:
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
if using_copy_on_write: # and copy is not True:
assert np.shares_memory(get_array(df2, "c"), get_array(df, "c"))
tm.assert_frame_equal(df, df_orig)


def test_drop_on_column(using_copy_on_write):
Expand Down Expand Up @@ -182,6 +199,7 @@ def test_select_dtypes(using_copy_on_write):
lambda x, y: x.align(y.a.iloc[slice(0, 1)], axis=1),
],
)
# TODO test copy keyword
def test_align_frame(using_copy_on_write, func):
df = DataFrame({"a": [1, 2, 3], "b": "a"})
df_orig = df.copy()
Expand Down Expand Up @@ -413,6 +431,7 @@ def test_assign_drop_duplicates(using_copy_on_write, method):
tm.assert_frame_equal(df, df_orig)


# TODO test copy keyword
def test_reindex_like(using_copy_on_write):
df = DataFrame({"a": [1, 2], "b": "a"})
other = DataFrame({"b": "a", "a": [1, 2]})
Expand Down Expand Up @@ -504,23 +523,29 @@ def test_swaplevel(using_copy_on_write, obj):
tm.assert_equal(obj, obj_orig)


def test_frame_set_axis(using_copy_on_write):
@pytest.mark.parametrize("copy", [True, None, False])
def test_frame_set_axis(using_copy_on_write, copy):
# GH 49473
df = DataFrame({"a": [1, 2, 3], "b": [4, 5, 6], "c": [0.1, 0.2, 0.3]})
df_orig = df.copy()
df2 = df.set_axis(["a", "b", "c"], axis="index")
df2 = df.set_axis(["a", "b", "c"], axis="index", copy=copy)

if using_copy_on_write:
if (using_copy_on_write and copy is not True) or copy is False:
assert np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
else:
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))

# mutating df2 triggers a copy-on-write for that column / block
df2.iloc[0, 0] = 0
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
tm.assert_frame_equal(df, df_orig)
if using_copy_on_write or copy is not False:
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
tm.assert_frame_equal(df, df_orig)
else:
assert np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
assert not df.equals(df_orig)


# TODO test copy keyword
def test_series_set_axis(using_copy_on_write):
# GH 49473
ser = Series([1, 2, 3])
Expand Down Expand Up @@ -556,22 +581,25 @@ def test_set_flags(using_copy_on_write):
tm.assert_series_equal(ser, expected)


@pytest.mark.parametrize("copy_kwargs", [{"copy": True}, {}])
@pytest.mark.parametrize("copy", [True, None, False])
@pytest.mark.parametrize("kwargs", [{"mapper": "test"}, {"index": "test"}])
def test_rename_axis(using_copy_on_write, kwargs, copy_kwargs):
def test_rename_axis(using_copy_on_write, kwargs, copy):
df = DataFrame({"a": [1, 2, 3, 4]}, index=Index([1, 2, 3, 4], name="a"))
df_orig = df.copy()
df2 = df.rename_axis(**kwargs, **copy_kwargs)
df2 = df.rename_axis(**kwargs, copy=copy)

if using_copy_on_write and not copy_kwargs:
if (using_copy_on_write and copy is not True) or copy is False:
assert np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
else:
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))

df2.iloc[0, 0] = 0
if using_copy_on_write:
if using_copy_on_write or copy is not False:
assert not np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
tm.assert_frame_equal(df, df_orig)
tm.assert_frame_equal(df, df_orig)
else:
assert np.shares_memory(get_array(df2, "a"), get_array(df, "a"))
assert not df.equals(df_orig)


@pytest.mark.parametrize(
Expand Down