Aluode/PerceptionLabPortable

1# Authors: The scikit-learn developers
2# SPDX-License-Identifier: BSD-3-Clause
3
4import math
5import numbers
6from contextlib import suppress
7
8
9def is_scalar_nan(x):
10    """Test if x is NaN.
11
12    This function is meant to overcome the issue that np.isnan does not allow
13    non-numerical types as input, and that np.nan is not float('nan').
14
15    Parameters
16    ----------
17    x : any type
18        Any scalar value.
19
20    Returns
21    -------
22    bool
23        Returns true if x is NaN, and false otherwise.
24
25    Examples
26    --------
27    >>> import numpy as np
28    >>> from sklearn.utils._missing import is_scalar_nan
29    >>> is_scalar_nan(np.nan)
30    True
31    >>> is_scalar_nan(float("nan"))
32    True
33    >>> is_scalar_nan(None)
34    False
35    >>> is_scalar_nan("")
36    False
37    >>> is_scalar_nan([np.nan])
38    False
39    """
40    return (
41        not isinstance(x, numbers.Integral)
42        and isinstance(x, numbers.Real)
43        and math.isnan(x)
44    )
45
46
47def is_pandas_na(x):
48    """Test if x is pandas.NA.
49
50    We intentionally do not use this function to return `True` for `pd.NA` in
51    `is_scalar_nan`, because estimators that support `pd.NA` are the exception
52    rather than the rule at the moment. When `pd.NA` is more universally
53    supported, we may reconsider this decision.
54
55    Parameters
56    ----------
57    x : any type
58
59    Returns
60    -------
61    boolean
62    """
63    with suppress(ImportError):
64        from pandas import NA
65
66        return x is NA
67
68    return False
69