On Mar 12, 3:38 pm, "Reedick, Andrew" <[EMAIL PROTECTED]> wrote:
[...]
> Start here
>
> http://www.mail-archive.com/[EMAIL PROTECTED]/msg178356.html
> and go through the thread. There are several ways to solve the problem
> and we evaluated the performance and 'pythonicity' of each.
I used a kind of extended cartesian product function a while ago while
writing a parser. If I simplify it down to a simple product function
it goes like this:
def product(*sequences):
i, n = 0, len(sequences)
vals = [None]*n
iters = map(iter, sequences)
while i >= 0:
if i == n:
yield tuple(vals)
i -= 1
else:
for vals[i] in iters[i]:
i += 1
break
else:
iters[i] = iter(sequences[i])
i -= 1
It's neither recursive nor a hack, I haven't tried to measure it
against other approaches (obviously it wouldn't beat the eval(...)
hack). I haven't optimised it for readability (by others) either :)
--
Arnaud
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