Inzynierka/Lib/site-packages/pandas/core/arrays/numeric.py
2023-06-02 12:51:02 +02:00

292 lines
9.0 KiB
Python

from __future__ import annotations
import numbers
from typing import (
TYPE_CHECKING,
Any,
Callable,
Mapping,
TypeVar,
)
import numpy as np
from pandas._libs import (
lib,
missing as libmissing,
)
from pandas._typing import (
Dtype,
DtypeObj,
npt,
)
from pandas.errors import AbstractMethodError
from pandas.util._decorators import cache_readonly
from pandas.core.dtypes.common import (
is_bool_dtype,
is_float_dtype,
is_integer_dtype,
is_object_dtype,
is_string_dtype,
pandas_dtype,
)
from pandas.core.arrays.masked import (
BaseMaskedArray,
BaseMaskedDtype,
)
if TYPE_CHECKING:
import pyarrow
T = TypeVar("T", bound="NumericArray")
class NumericDtype(BaseMaskedDtype):
_default_np_dtype: np.dtype
_checker: Callable[[Any], bool] # is_foo_dtype
def __repr__(self) -> str:
return f"{self.name}Dtype()"
@cache_readonly
def is_signed_integer(self) -> bool:
return self.kind == "i"
@cache_readonly
def is_unsigned_integer(self) -> bool:
return self.kind == "u"
@property
def _is_numeric(self) -> bool:
return True
def __from_arrow__(
self, array: pyarrow.Array | pyarrow.ChunkedArray
) -> BaseMaskedArray:
"""
Construct IntegerArray/FloatingArray from pyarrow Array/ChunkedArray.
"""
import pyarrow
from pandas.core.arrays.arrow._arrow_utils import (
pyarrow_array_to_numpy_and_mask,
)
array_class = self.construct_array_type()
pyarrow_type = pyarrow.from_numpy_dtype(self.type)
if not array.type.equals(pyarrow_type):
# test_from_arrow_type_error raise for string, but allow
# through itemsize conversion GH#31896
rt_dtype = pandas_dtype(array.type.to_pandas_dtype())
if rt_dtype.kind not in ["i", "u", "f"]:
# Could allow "c" or potentially disallow float<->int conversion,
# but at the moment we specifically test that uint<->int works
raise TypeError(
f"Expected array of {self} type, got {array.type} instead"
)
array = array.cast(pyarrow_type)
if isinstance(array, pyarrow.Array):
chunks = [array]
else:
# pyarrow.ChunkedArray
chunks = array.chunks
results = []
for arr in chunks:
data, mask = pyarrow_array_to_numpy_and_mask(arr, dtype=self.numpy_dtype)
num_arr = array_class(data.copy(), ~mask, copy=False)
results.append(num_arr)
if not results:
return array_class(
np.array([], dtype=self.numpy_dtype), np.array([], dtype=np.bool_)
)
elif len(results) == 1:
# avoid additional copy in _concat_same_type
return results[0]
else:
return array_class._concat_same_type(results)
@classmethod
def _str_to_dtype_mapping(cls) -> Mapping[str, NumericDtype]:
raise AbstractMethodError(cls)
@classmethod
def _standardize_dtype(cls, dtype: NumericDtype | str | np.dtype) -> NumericDtype:
"""
Convert a string representation or a numpy dtype to NumericDtype.
"""
if isinstance(dtype, str) and (dtype.startswith(("Int", "UInt", "Float"))):
# Avoid DeprecationWarning from NumPy about np.dtype("Int64")
# https://github.com/numpy/numpy/pull/7476
dtype = dtype.lower()
if not isinstance(dtype, NumericDtype):
mapping = cls._str_to_dtype_mapping()
try:
dtype = mapping[str(np.dtype(dtype))]
except KeyError as err:
raise ValueError(f"invalid dtype specified {dtype}") from err
return dtype
@classmethod
def _safe_cast(cls, values: np.ndarray, dtype: np.dtype, copy: bool) -> np.ndarray:
"""
Safely cast the values to the given dtype.
"safe" in this context means the casting is lossless.
"""
raise AbstractMethodError(cls)
def _coerce_to_data_and_mask(values, mask, dtype, copy, dtype_cls, default_dtype):
checker = dtype_cls._checker
inferred_type = None
if dtype is None and hasattr(values, "dtype"):
if checker(values.dtype):
dtype = values.dtype
if dtype is not None:
dtype = dtype_cls._standardize_dtype(dtype)
cls = dtype_cls.construct_array_type()
if isinstance(values, cls):
values, mask = values._data, values._mask
if dtype is not None:
values = values.astype(dtype.numpy_dtype, copy=False)
if copy:
values = values.copy()
mask = mask.copy()
return values, mask, dtype, inferred_type
original = values
values = np.array(values, copy=copy)
inferred_type = None
if is_object_dtype(values.dtype) or is_string_dtype(values.dtype):
inferred_type = lib.infer_dtype(values, skipna=True)
if inferred_type == "boolean" and dtype is None:
name = dtype_cls.__name__.strip("_")
raise TypeError(f"{values.dtype} cannot be converted to {name}")
elif is_bool_dtype(values) and checker(dtype):
values = np.array(values, dtype=default_dtype, copy=copy)
elif not (is_integer_dtype(values) or is_float_dtype(values)):
name = dtype_cls.__name__.strip("_")
raise TypeError(f"{values.dtype} cannot be converted to {name}")
if values.ndim != 1:
raise TypeError("values must be a 1D list-like")
if mask is None:
if is_integer_dtype(values):
# fastpath
mask = np.zeros(len(values), dtype=np.bool_)
else:
mask = libmissing.is_numeric_na(values)
else:
assert len(mask) == len(values)
if mask.ndim != 1:
raise TypeError("mask must be a 1D list-like")
# infer dtype if needed
if dtype is None:
dtype = default_dtype
else:
dtype = dtype.type
if is_integer_dtype(dtype) and is_float_dtype(values.dtype) and len(values) > 0:
if mask.all():
values = np.ones(values.shape, dtype=dtype)
else:
idx = np.nanargmax(values)
if int(values[idx]) != original[idx]:
# We have ints that lost precision during the cast.
inferred_type = lib.infer_dtype(original, skipna=True)
if (
inferred_type not in ["floating", "mixed-integer-float"]
and not mask.any()
):
values = np.array(original, dtype=dtype, copy=False)
else:
values = np.array(original, dtype="object", copy=False)
# we copy as need to coerce here
if mask.any():
values = values.copy()
values[mask] = cls._internal_fill_value
if inferred_type in ("string", "unicode"):
# casts from str are always safe since they raise
# a ValueError if the str cannot be parsed into a float
values = values.astype(dtype, copy=copy)
else:
values = dtype_cls._safe_cast(values, dtype, copy=False)
return values, mask, dtype, inferred_type
class NumericArray(BaseMaskedArray):
"""
Base class for IntegerArray and FloatingArray.
"""
_dtype_cls: type[NumericDtype]
def __init__(
self, values: np.ndarray, mask: npt.NDArray[np.bool_], copy: bool = False
) -> None:
checker = self._dtype_cls._checker
if not (isinstance(values, np.ndarray) and checker(values.dtype)):
descr = (
"floating"
if self._dtype_cls.kind == "f" # type: ignore[comparison-overlap]
else "integer"
)
raise TypeError(
f"values should be {descr} numpy array. Use "
"the 'pd.array' function instead"
)
if values.dtype == np.float16:
# If we don't raise here, then accessing self.dtype would raise
raise TypeError("FloatingArray does not support np.float16 dtype.")
super().__init__(values, mask, copy=copy)
@cache_readonly
def dtype(self) -> NumericDtype:
mapping = self._dtype_cls._str_to_dtype_mapping()
return mapping[str(self._data.dtype)]
@classmethod
def _coerce_to_array(
cls, value, *, dtype: DtypeObj, copy: bool = False
) -> tuple[np.ndarray, np.ndarray]:
dtype_cls = cls._dtype_cls
default_dtype = dtype_cls._default_np_dtype
mask = None
values, mask, _, _ = _coerce_to_data_and_mask(
value, mask, dtype, copy, dtype_cls, default_dtype
)
return values, mask
@classmethod
def _from_sequence_of_strings(
cls: type[T], strings, *, dtype: Dtype | None = None, copy: bool = False
) -> T:
from pandas.core.tools.numeric import to_numeric
scalars = to_numeric(strings, errors="raise", dtype_backend="numpy_nullable")
return cls._from_sequence(scalars, dtype=dtype, copy=copy)
_HANDLED_TYPES = (np.ndarray, numbers.Number)