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BUG: na parameter for str.startswith and str.endswith not propagating for Series with categorical dtype #36249

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Merged
merged 10 commits into from
Sep 12, 2020
Merged

BUG: na parameter for str.startswith and str.endswith not propagating for Series with categorical dtype #36249

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e9a418d
add breaking test
asishm Sep 9, 2020
1a5cf4f
propagate na to _wrap_result
asishm Sep 9, 2020
2f90e6b
add string, fill value and null value parametrize
asishm Sep 11, 2020
54e486e
add na=True/False param to string tests; parametrize over na and null…
asishm Sep 11, 2020
70b6e3c
Merge branch 'master' of github.com:pandas-dev/pandas into strmethods
asishm Sep 11, 2020
44d386e
add whatsnew note
asishm Sep 11, 2020
5e3be5a
black
asishm Sep 11, 2020
d8e5bb7
Update doc/source/whatsnew/v1.1.3.rst
asishm Sep 11, 2020
1467a0a
make expected series explicit
asishm Sep 12, 2020
9d0070c
Merge branch 'strmethods' of github.com:asishm/pandas into strmethods
asishm Sep 12, 2020
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2 changes: 1 addition & 1 deletion pandas/core/strings.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2050,7 +2050,7 @@ def wrapper2(self, pat, flags=0, **kwargs):
@forbid_nonstring_types(forbidden_types, name=name)
def wrapper3(self, pat, na=np.nan):
result = f(self._parent, pat, na=na)
return self._wrap_result(result, returns_string=returns_string)
return self._wrap_result(result, returns_string=returns_string, fill_value=na)

wrapper = wrapper3 if na else wrapper2 if flags else wrapper1

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16 changes: 12 additions & 4 deletions pandas/tests/test_strings.py
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Expand Up @@ -838,8 +838,12 @@ def test_contains_for_object_category(self):
expected = Series([True, False, False, True, False])
tm.assert_series_equal(result, expected)

def test_startswith(self):
values = Series(["om", np.nan, "foo_nom", "nom", "bar_foo", np.nan, "foo"])
# add category dtype parametrizations for GH-36241
@pytest.mark.parametrize("dtype", [None, "category"])
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we want to parameterize over 'string' dtype as well rigth?

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string arrays are already tested here
https://github.com/pandas-dev/pandas/blob/1.1.x/pandas/tests/test_strings.py#L3530-L3531

parametrizing over string dtype and na=True/False was making it a bit tricky as these methods return boolean series causing a dtype mismatch (boolean vs object)

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@jreback tried to do that changing the referenced tests slightly with
https://github.com/pandas-dev/pandas/pull/36249/files#diff-683f8dacd08abda4913680fafe3a4ea7R3573-R3576 , https://github.com/pandas-dev/pandas/pull/36249/files#diff-683f8dacd08abda4913680fafe3a4ea7R32-R33 and https://github.com/pandas-dev/pandas/pull/36249/files#diff-683f8dacd08abda4913680fafe3a4ea7R63-R64

def test_startswith(self, dtype):
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I think we would want to parameterize over different fill values to test the behavior from the OP

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@asishm asishm Sep 11, 2020 •
edited
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parameterized over True, False

question here:

for string Series with dtype = object, passing strings into the na parameter of these two methods causes it to replace the nan with the string - but for StringArrays it replaces the nans with bool(na). The current fix behaves as the former.

In [49]: pd.Series(['a', np.nan, 'b']).str.startswith('a', na='c')
Out[49]:
0     True
1        c
2    False
dtype: object

In [50]: pd.Series(['a', np.nan, 'b'], dtype='string').str.startswith('a', na='c')
Out[50]:
0     True
1     True
2    False
dtype: boolean

In [53]: pd.Series(['a', np.nan, 'b'], dtype='category').str.startswith('a', na='c')
Out[53]: 
0     True
1        c
2    False
dtype: object

edits: copying the wrong cells!!

values = Series(
["om", np.nan, "foo_nom", "nom", "bar_foo", np.nan, "foo"], dtype=dtype
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also pls tests with pd.NA as well (you can parameterize over the null value as well

)

result = values.str.startswith("foo")
exp = Series([False, np.nan, True, False, False, np.nan, True])
Expand Down Expand Up @@ -867,8 +871,12 @@ def test_startswith(self):
)
tm.assert_series_equal(rs, xp)

def test_endswith(self):
values = Series(["om", np.nan, "foo_nom", "nom", "bar_foo", np.nan, "foo"])
# add category dtype parametrizations for GH-36241
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add inside the test

@pytest.mark.parametrize("dtype", [None, "category"])
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same as above

def test_endswith(self, dtype):
values = Series(
["om", np.nan, "foo_nom", "nom", "bar_foo", np.nan, "foo"], dtype=dtype
)

result = values.str.endswith("foo")
exp = Series([False, np.nan, False, False, True, np.nan, True])
Expand Down