heapq.py 文件源码

def nsmallest(n, iterable):
    """Find the n smallest elements in a dataset.

    Equivalent to:  sorted(iterable)[:n]
    """
    if n < 0:
        return []
    it = iter(iterable)
    result = list(islice(it, n))
    if not result:
        return result
    _heapify_max(result)
    _heappushpop = _heappushpop_max
    for elem in it:
        _heappushpop(result, elem)
    result.sort()
    return result

# 'heap' is a heap at all indices >= startpos, except possibly for pos.  pos
# is the index of a leaf with a possibly out-of-order value.  Restore the
# heap invariant.