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REGR: read_csv raising when dtypes is specified with usecols #54881

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Merged
merged 4 commits into from
Sep 1, 2023
Merged

REGR: read_csv raising when dtypes is specified with usecols #54881

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REGR: read_csv raising when dtypes is specified with usecols
phofl Aug 30, 2023
e4c6fe2
Update
phofl Aug 31, 2023
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Merge remote-tracking branch 'upstream/main' into 54868
phofl Aug 31, 2023
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phofl Aug 31, 2023
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2 changes: 1 addition & 1 deletion pandas/io/parsers/python_parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1176,7 +1176,7 @@ def _set_no_thousand_columns(self) -> set[int]:
)
if self.columns and self.dtype:
assert self._col_indices is not None
for i in self._col_indices:
for i, idx in enumerate(self._col_indices):
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Suggested change
for i, idx in enumerate(self._col_indices):
for i, col in zip(self._col_indices, self.columns):

and then self.columns[i] can just be replaced with col?

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yep thx

if not isinstance(self.dtype, dict) and not is_numeric_dtype(
self.dtype
):
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17 changes: 17 additions & 0 deletions pandas/tests/io/parser/dtypes/test_dtypes_basic.py
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Expand Up @@ -575,3 +575,20 @@ def test_accurate_parsing_of_large_integers(all_parsers):
assert len(orders.loc[orders["ID_DEAL"] == 2023552585717263359, "ID_DEAL"]) == 1
assert len(orders.loc[orders["ID_DEAL"] == 2023552585717263360, "ID_DEAL"]) == 2
assert len(orders.loc[orders["ID_DEAL"] == 2023552585717263361, "ID_DEAL"]) == 2


def test_dtypes_with_usecols(all_parsers):
# GH#54868

parser = all_parsers
data = """a,b,c
1,2,3
4,5,6"""

result = parser.read_csv(StringIO(data), usecols=["a", "c"], dtype={"a": object})
if parser.engine == "pyarrow":
values = [1, 4]
else:
values = ["1", "4"]
expected = DataFrame({"a": pd.Series(values, dtype=object), "c": [3, 6]})
tm.assert_frame_equal(result, expected)