simfunctions.py 文件源码

def hamming_distance(string1, string2):
    """
    Computes the Hamming distance between two strings.

    The Hamming distance between two strings of equal length is the number of positions at which the corresponding
    symbols are different. In another way, it measures the minimum number of substitutions required to change
    one string into the other, or the minimum number of errors that could have transformed one string into the other.


    Args:
        string1,string2 (str): Input strings

    Returns:
        Hamming distance (int)

    Raises:
        TypeError : If the inputs are not strings or if one of the inputs is None.
        ValueError : If the input strings are not of same length


    Examples:
        >>> hamming_distance('', '')
        0
        >>> hamming_distance('alex', 'john')
        4
        >>> hamming_distance(' ', 'a')
        0
        >>> hamming_distance('JOHN', 'john')
        4
    """
    # input validations
    utils.sim_check_for_none(string1, string2)
    utils.tok_check_for_string_input(string1, string2)
    # for Hamming Distance string length should be same
    utils.sim_check_for_same_len(string1, string2)
    # sum all the mismatch characters at the corresponding index of
    # input strings
    return sum(bool(ord(c1) - ord(c2)) for c1, c2 in zip(string1, string2))