TheAlgorithms-Python

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"""
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Signum function -- https://en.wikipedia.org/wiki/Sign_function
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"""
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def signum(num: float) -> int:
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    """
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    Applies signum function on the number
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    Custom test cases:
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    >>> signum(-10)
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    -1
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    >>> signum(10)
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    1
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    >>> signum(0)
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    0
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    >>> signum(-20.5)
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    -1
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    >>> signum(20.5)
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    1
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    >>> signum(-1e-6)
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    -1
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    >>> signum(1e-6)
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    1
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    >>> signum("Hello")
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    Traceback (most recent call last):
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        ...
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    TypeError: '<' not supported between instances of 'str' and 'int'
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    >>> signum([])
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    Traceback (most recent call last):
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        ...
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    TypeError: '<' not supported between instances of 'list' and 'int'
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    """
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    if num < 0:
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        return -1
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    return 1 if num else 0
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def test_signum() -> None:
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    """
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    Tests the signum function
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    >>> test_signum()
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    """
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    assert signum(5) == 1
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    assert signum(-5) == -1
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    assert signum(0) == 0
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    assert signum(10.5) == 1
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    assert signum(-10.5) == -1
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    assert signum(1e-6) == 1
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    assert signum(-1e-6) == -1
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    assert signum(123456789) == 1
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    assert signum(-123456789) == -1
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if __name__ == "__main__":
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    print(signum(12))
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    print(signum(-12))
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    print(signum(0))
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