在python中使用块大小序列的石斑鱼？

Question

我有一个生成器,我想在两个级别迭代.第一级是不均匀的间隔,然后我想将下一级别分成5组,比方说.我需要它以节省内存并处理生成器输入,所以我正在做类似以下的事情.我不得不认为可能有更好的方法吗？特别是,我不希望在不均匀的长度结果中跟踪Nones.

import itertools

def dynamic_grouper(iterable, intervals):
    for i in intervals:
        inner_iter = list(itertools.islice(iterable, i)) # this is a "group"
        yield inner_iter

iterable = iter(xrange(100))
chunk_sizes = [22,30,38,10]

for i,group in enumerate(dynamic_grouper(iterable, chunk_sizes)):
    args = [iter(group)] * 5
    for item in itertools.izip_longest(fillvalue=None, *args):
        print "Group %i" % i
        print "Items %s" % list(item)

Answer 1

要避免使用Nones,您可以使用块:

def chunks(seq, n):
    # https://stackoverflow.com/a/312464/190597 (Ned Batchelder)
    """ Yield successive n-sized chunks from seq."""
    for i in xrange(0, len(seq), n):
        yield seq[i:i + n]

for i,group in enumerate(dynamic_grouper(iterable, chunk_sizes)):
    for item in chunks(group, 5):
        print "Group %i" % i
        print "Items %s" % list(item)