Viewing file:  IterPermute.py (1.79 KB) -rw-r--r--
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#._cv_part guppy.etc.IterPermute
def iterpermute(*args):
args = [iter(a) for a in args]
la = len(args)
stopped = [0] * la
lens = [0] * la
bufs = [[] for i in range(la)]
nexts = [None] * la
n = 0
while 1:
anynew = 0
for i in range(la):
if stopped[i]:
next = bufs[i][n%lens[i]]
else:
try:
next = args[i].next()
except StopIteration:
if lens[i] == 0:
# raise ValueError, 'The iterator passed in arg %d did not return any item'%i
return
stopped[i] = 1
next = bufs[i][n%lens[i]]
else:
anynew = 1
bufs[i].append(next)
lens[i] += 1
nexts[i] = next
if anynew:
n += 1
yield tuple(nexts)
else:
break
wanted = reduce(lambda x, y: x*y, lens, 1)
if n >= wanted:
assert n == wanted
return
ixs = list(enumerate(lens))
ixs.sort(lambda (ixa, lna), (ixb, lnb) : cmp(lna, lnb))
ixs = [ix for (ix,ln) in ixs]
jxs = [0] * la
seen = dict([(tuple([j%lens[i] for i in ixs]), 1)
for j in range(n)])
while n < wanted:
t = tuple([jxs[i] for i in ixs])
if t not in seen:
yield tuple([bufs[i][jxs[i]] for i in range(la)])
n += 1
for i in ixs:
j = jxs[i]
j = (j + 1)%lens[i]
jxs[i] = j
if j != 0:
break
def test_iterpermute():
import itertools
repeat = itertools.repeat
assert list(iterpermute()) == [()]
assert list(iterpermute(repeat(1, 2))) == [(1,), (1,)]
assert list(iterpermute(repeat(1, 1), repeat(2, 1))) == [(1,2)]
assert list(iterpermute(range(0,2), range(2,3))) == [(0, 2), (1, 2)]
assert list(iterpermute(range(0,2), range(2,4))) == [(0, 2), (1, 3), (1, 2), (0, 3)]
print list(iterpermute(range(0,2), range(0,3)))
print list(iterpermute(range(0,3), range(0,2)))
if __name__ == '__main__':
test_iterpermute()
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