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BUG: clip doesn't preserve dtype by column #24458

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Merged
merged 6 commits into from
Dec 28, 2018
Merged

BUG: clip doesn't preserve dtype by column #24458

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31f8567
use self.where method instead of numpy where to reuse casting logics
minggli Dec 27, 2018
61bb0c8
modify clip scalar
minggli Dec 27, 2018
7235940
modify expected case
minggli Dec 27, 2018
b5a6121
use existing handling of inplace
minggli Dec 28, 2018
45bd478
add test case
minggli Dec 28, 2018
fab5c99
update whatsnew
minggli Dec 28, 2018
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27 changes: 10 additions & 17 deletions pandas/core/generic.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7132,28 +7132,21 @@ def _clip_with_scalar(self, lower, upper, inplace=False):
(upper is not None and np.any(isna(upper)))):
raise ValueError("Cannot use an NA value as a clip threshold")

result = self.values
mask = isna(result)

with np.errstate(all='ignore'):
if upper is not None:
result = np.where(result >= upper, upper, result)
if lower is not None:
result = np.where(result <= lower, lower, result)
if np.any(mask):
result[mask] = np.nan
result = self

axes_dict = self._construct_axes_dict()
result = self._constructor(result, **axes_dict).__finalize__(self)
if upper is not None:
subset = self.le(upper, axis=None) | isna(result)
result = result.where(subset, upper, axis=None, inplace=inplace)
if lower is not None:
if inplace:
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Why is this inplace check only when lower is not None? It looks like you also assign result = self before the upper and lower check.

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Hi @mroeschke, thanks for reviewing!

result = self is to ensure there is a return value in case both lower and upper are None, which they can. when inplace=True, result is None

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Got it. Thanks!

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I think its just better to use the existing idiom

if inplace:
     self._update_inplace(result0
else:
    return self

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actioned. thanks.

result = self
subset = self.ge(lower, axis=None) | isna(result)
result = result.where(subset, lower, axis=None, inplace=inplace)

if inplace:
self._update_inplace(result)
else:
return result
return result

def _clip_with_one_bound(self, threshold, method, axis, inplace):

inplace = validate_bool_kwarg(inplace, 'inplace')
if axis is not None:
axis = self._get_axis_number(axis)

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3 changes: 2 additions & 1 deletion pandas/tests/frame/test_analytics.py
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Expand Up @@ -1895,7 +1895,8 @@ def test_clip_mixed_numeric(self):
df = DataFrame({'A': [1, 2, 3],
'B': [1., np.nan, 3.]})
result = df.clip(1, 2)
expected = DataFrame({'A': [1, 2, 2.],
# GH 24162, clipping now preserves types
expected = DataFrame({'A': [1, 2, 2],
'B': [1., np.nan, 2.]})
tm.assert_frame_equal(result, expected, check_like=True)

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