Here's toolz.itertoolz.interleave():
def interleave(seqs):
""" Interleave a sequence of sequences
>>> list(interleave([[1, 2], [3, 4]]))
[1, 3, 2, 4]
>>> ''.join(interleave(('ABC', 'XY')))
'AXBYC'
Both the individual sequences and the sequence of sequences may be
infinite
Returns a lazy iterator
"""
iters = itertools.cycle(map(iter, seqs))
while True:
try:
for itr in iters:
yield next(itr)
return
except StopIteration:
predicate = partial(operator.is_not, itr)
iters = itertools.cycle(itertools.takewhile(predicate, iters))
At first glance, map should be e.g. six.moves.map for pythonic backward
compatibility.
Is this slower than the linear time implementations listed here?
On Tuesday, November 21, 2017, Alon Snir <[email protected]> wrote:
> def roundrobin(*iterables):
> "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
> nexts = [ iter(it).__next__ for it in iterables ]
> i = 0
> while nexts:
> i %= len(nexts)
> try:
> yield nexts[i]()
> except StopIteration:
> del nexts[i]
> else:
> i += 1
>
> Regards
> Alon Snir
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