iterfunction.py 文件源码

def unique(iterable, key=None):
    """
    Return only unique elements in iterable. Potentially high mem. consumption!

    >>> list(unique([2,3,1,1,2,4]))
    [2, 3, 1, 4]

    >>> ''.join(unique('this is a test'))
    'this ae'

    >>> data = [(1,'a'), (2,'a'), (3,'b')]
    >>> list(unique(data, key=lambda t: t[1]))
    [(1, 'a'), (3, 'b')]

    :param iterable iterable: Any iterable, e.g. list, range, ...
    :param key: Function used to compare for equality.
    :return: Iterator over unique elements.
    :rtype: Iterator
    """
    seen = set()
    for e in iterable:
        k = key(e) if key else e
        if k not in seen:
            seen.add(k)
            yield e