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BUG: infer_dtype with decimal/complex #37176

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Oct 18, 2020
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25 changes: 21 additions & 4 deletions pandas/_libs/lib.pyx
Original file line number Diff line number Diff line change
Expand Up @@ -1414,10 +1414,12 @@ def infer_dtype(value: object, skipna: bool = True) -> str:
return "time"

elif is_decimal(val):
return "decimal"
if all(is_decimal(x) for x in values):
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can you create is_decimal_array to have the same style

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i think you actually want to use the validator e.g as a raw NaN would not work here

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can you expand on this? do you expect something other than Decimal objects to work here?

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NaNs are valid as well here; but more important is that every validator has the same pattern. a is_* function e.g. is_decimal_array, which should call here.

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updated to use the is_* pattern.

since decimal has Decimal("nan"), i wouldnt expect to accept np.nan here

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since decimal has Decimal("nan"), i wouldnt expect to accept np.nan here

yeah ok, though i think we could actually accept np.nan as well and infer a decimal if that is the case (as we do this for all other dtypes). can you open an issue.

return "decimal"

elif is_complex(val):
return "complex"
if is_complex_array(values):
return "complex"

elif util.is_float_object(val):
if is_float_array(values):
Expand Down Expand Up @@ -1702,6 +1704,23 @@ cpdef bint is_float_array(ndarray values):
return validator.validate(values)


cdef class ComplexValidator(Validator):
cdef inline bint is_value_typed(self, object value) except -1:
return (
util.is_complex_object(value)
or (util.is_float_object(value) and is_nan(value))
)

cdef inline bint is_array_typed(self) except -1:
return issubclass(self.dtype.type, np.complexfloating)


cdef bint is_complex_array(ndarray values):
cdef:
ComplexValidator validator = ComplexValidator(len(values), values.dtype)
return validator.validate(values)


cdef class StringValidator(Validator):
cdef inline bint is_value_typed(self, object value) except -1:
return isinstance(value, str)
Expand Down Expand Up @@ -2546,8 +2565,6 @@ def fast_multiget(dict mapping, ndarray keys, default=np.nan):
# kludge, for Series
return np.empty(0, dtype='f8')

keys = getattr(keys, 'values', keys)

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unrelated cleanup

for i in range(n):
val = keys[i]
if val in mapping:
Expand Down
6 changes: 6 additions & 0 deletions pandas/tests/dtypes/test_inference.py
Original file line number Diff line number Diff line change
Expand Up @@ -709,6 +709,9 @@ def test_decimals(self):
result = lib.infer_dtype(arr, skipna=True)
assert result == "mixed"

result = lib.infer_dtype(arr[::-1], skipna=True)
assert result == "mixed"

arr = np.array([Decimal(1), Decimal("NaN"), Decimal(3)])
result = lib.infer_dtype(arr, skipna=True)
assert result == "decimal"
Expand All @@ -729,6 +732,9 @@ def test_complex(self, skipna):
result = lib.infer_dtype(arr, skipna=skipna)
assert result == "mixed"

result = lib.infer_dtype(arr[::-1], skipna=skipna)
assert result == "mixed"

# gets cast to complex on array construction
arr = np.array([1, np.nan, 1 + 1j])
result = lib.infer_dtype(arr, skipna=skipna)
Expand Down