Am 25.10.2012 01:39 schrieb Ian Kelly:
On Wed, Oct 24, 2012 at 5:08 PM, Paul Rubin <no.email@nospam.invalid> wrote:
from itertools import dropwhile
j = dropwhile(lambda j: j in selected,
iter(lambda: int(random() * n), object()))
.next()
kind of ugly, makes me wish for a few more itertools primitives, but I
think it expresses reasonably directly what you are trying to do.
Nice, although a bit opaque. I think I prefer it as a generator expression:
j = next(j for j in iter(partial(randrange, n), None) if j not in selected)
This generator never ends. If it meets a non-matching value, it just
skips it and goes on.
The dropwhile expression, however, stops as soon as the value is found.
I think
# iterate ad inf., because partial never returns None:
i1 = iter(partial(randrange, n), None)
# take the next value, make it None for breaking:
i2 = (j if j in selected else None for j in i1)
# and now, break on None:
i3 = iter(lambda: next(i2), None)
would do the job.
Thomas
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