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BUG: replace with value also being replaced #46335

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Merged
merged 5 commits into from
Mar 12, 2022
Merged

BUG: replace with value also being replaced #46335

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c00f981
bug: replace with value also being replaced
lukemanley Mar 12, 2022
75cc610
updates
lukemanley Mar 12, 2022
6ab4e8f
mypy
lukemanley Mar 12, 2022
411c6c3
fixup
lukemanley Mar 12, 2022
57a33a6
fix mask indexer
lukemanley Mar 12, 2022
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12 changes: 9 additions & 3 deletions pandas/core/internals/blocks.py
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Original file line number Diff line number Diff line change
Expand Up @@ -612,9 +612,15 @@ def replace(

else:
# split so that we only upcast where necessary
return self.split_and_operate(
type(self).replace, to_replace, value, inplace=True
)
blocks = []
nbs = self._split()
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could write this entire section as a list-comprehension, but maybe not as readable

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good idea, i like the list comprehension better

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Went back to a non-list comprehension implementation as it requires unpacking.

for i, nb in enumerate(nbs):
submask = mask[i]
rbs = type(self).replace(
nb, to_replace, value, inplace=True, mask=submask
)
blocks.extend(rbs)
return blocks

@final
def _replace_regex(
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7 changes: 7 additions & 0 deletions pandas/tests/frame/methods/test_replace.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1542,3 +1542,10 @@ def test_replace_regex_dtype_frame(self, regex):
expected_df2 = DataFrame({"A": [1], "B": ["1"]})
result_df2 = df2.replace(to_replace="0", value=1, regex=regex)
tm.assert_frame_equal(result_df2, expected_df2)

def test_replace_with_value_also_being_replaced(self):
# GH46306
df = DataFrame({"A": [0, 1, 2], "B": [1, 0, 2]})
result = df.replace({0: 1, 1: np.nan})
expected = DataFrame({"A": [1, np.nan, 2], "B": [np.nan, 1, 2]})
tm.assert_frame_equal(result, expected)