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REF: collect casting portion of Block.setitem #32940

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Merged
merged 1 commit into from
Mar 25, 2020
Merged

REF: collect casting portion of Block.setitem #32940

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30 changes: 12 additions & 18 deletions pandas/core/internals/blocks.py
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Original file line number Diff line number Diff line change
Expand Up @@ -833,21 +833,24 @@ def setitem(self, indexer, value):

else:
# current dtype cannot store value, coerce to common dtype
find_dtype = False

if hasattr(value, "dtype"):
dtype = value.dtype
find_dtype = True

elif lib.is_scalar(value) and not isna(value):
dtype, _ = infer_dtype_from_scalar(value, pandas_dtype=True)
find_dtype = True

if find_dtype:
dtype = find_common_type([values.dtype, dtype])
if not is_dtype_equal(self.dtype, dtype):
b = self.astype(dtype)
return b.setitem(indexer, value)
else:
# e.g. we are bool dtype and value is nan
# TODO: watch out for case with listlike value and scalar/empty indexer
dtype, _ = maybe_promote(np.array(value).dtype)
return self.astype(dtype).setitem(indexer, value)

dtype = find_common_type([values.dtype, dtype])
assert not is_dtype_equal(self.dtype, dtype)
# otherwise should have _can_hold_element

return self.astype(dtype).setitem(indexer, value)
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do we do copy=False internally in .astype?

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That's the default kwarg for Block.astype, yes


# value must be storeable at this moment
if is_extension_array_dtype(getattr(value, "dtype", None)):
Expand All @@ -857,11 +860,6 @@ def setitem(self, indexer, value):
else:
arr_value = np.array(value)

# cast the values to a type that can hold nan (if necessary)
if not self._can_hold_element(value):
dtype, _ = maybe_promote(arr_value.dtype)
values = values.astype(dtype)

if transpose:
values = values.T

Expand All @@ -881,11 +879,7 @@ def setitem(self, indexer, value):
# be e.g. a list; see GH#6043
values[indexer] = value

elif (
exact_match
and is_categorical_dtype(arr_value.dtype)
and not is_categorical_dtype(values)
):
elif exact_match and is_categorical_dtype(arr_value.dtype):
# GH25495 - If the current dtype is not categorical,
# we need to create a new categorical block
values[indexer] = value
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