Re: [Python-ideas] Function to unnest for-statements

May 23, 2008

      On Fri, 23 May 2008, Leif Walsh wrote:
...
I've worked this out (I'm sure I did this in intro CS once before...),
although there is probably some optimization trick I'm missing, and
I'm probably doing some silly double-allocation thing or something.
...
...
...
def combine(lists):
...     if len(lists) is 0:
...             return [[]]
...     first = combine(lists[0:-1])
...     total = []
...     for item in lists[-1]:
...             total += [[item] + subset for subset in first]
...     return total
Oops, that should probably be:

...     for subset in first:
...             total += [subset + [item] for item in lists[-1]]

to maintain order.  My excuse is that it's past my bedtime.

-- 
Cheers,
Leif