utils.py

# Copyright (c) 2023, Haruka Kiyohara, Ren Kishimoto, HAKUHODO Technologies Inc., and Hanjuku-kaso Co., Ltd. All rights reserved.
# Licensed under the Apache 2.0 License.


"""Useful tools."""
from typing import Union, Optional

import numpy as np


def sigmoid(x: Union[float, np.ndarray]) -> Union[float, np.ndarray]:
    """Sigmoid function"""
    return 1 / (1 + np.exp(-x))


def check_array(
    array: np.ndarray,
    name: str,
    expected_dim: int = 1,
    expected_dtype: Optional[type] = None,
    min_val: Optional[float] = None,
    max_val: Optional[float] = None,
) -> ValueError:
    """Input validation on array.

    Parameters
    -------
    array: object
        Input array to check.

    name: str
        Name of the input array.

    expected_dim: int, default=1
        Expected dimension of the input array.

    expected_dtype: {type, tuple of type}, default=None
        Expected dtype of the input array.

    min_val: float, default=None
        Minimum value allowed in the input array.

    max_val: float, default=None
        Maximum value allowed in the input array.

    """
    if not isinstance(array, np.ndarray):
        raise ValueError(f"{name} must be {expected_dim}D array, but got {type(array)}")
    if array.ndim != expected_dim:
        raise ValueError(
            f"{name} must be {expected_dim}D array, but got {expected_dim}D array"
        )
    if expected_dtype is not None:
        if not np.issubsctype(array, expected_dtype):
            raise ValueError(
                f"The elements of {name} must be {expected_dtype}, but got {array.dtype}"
            )
    if min_val is not None:
        if array.min() < min_val:
            raise ValueError(
                f"The elements of {name} must be larger than {min_val}, but got minimum value {array.min()}"
            )
    if max_val is not None:
        if array.max() > max_val:
            raise ValueError(
                f"The elements of {name} must be smaller than {max_val}, but got maximum value {array.max()}"
            )