On 07 Apr 2009 02:05:59 GMT
Steven D'Aprano <ste...@remove.this.cybersource.com.au> wrote:
> The demuxer can't be an iterator, since it needs to run through the
> entire collection.
Then your demuxer obviously cannot handle infinite sequences.
> def demux(it, n):
> collectors = [[] for i in xrange(n)]
> i = 0
> for item in it:
> collectors[i].append(item)
> i = (i+1) % n
> return tuple([iter(x) for x in collectors])
But this one can:
from collections import deque
from itertools import cycle, izip, count, islice
def mux(*iterables):
for it in izip(*iterables):
for item in it:
yield item
def demux(seq,n):
it = iter(seq)
Q = [deque() for i in xrange(n)]
CQ = cycle(Q)
def gen(D):
for x,C in izip(it,CQ):
C.appendleft(x)
while D:
yield D.pop()
while D:
yield D.pop()
return map(gen,Q)
def test():
a = count(10)
b = count(20)
c = count (30)
x = demux(mux(a,b,c),3)
for e in x:
print list(islice(e,0,10))
if __name__=='__main__':
test()
P.
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