On 28/02/07, Smith, Jeff <[EMAIL PROTECTED]> wrote: > I realize however that this is probably much less efficient since you > are iterating over the inner list rather than just taking it on in > whole.
Well, you know what they say --- don't guess, profile :-) Morpork:~ repton$ python -m timeit -s 'lsts=[["a","b","c"],["1","2","3"],["x","y","z"]]' 'flattened = [x for l in lsts for x in l]' 100000 loops, best of 3: 3.9 usec per loop Morpork:~ repton$ python -m timeit -s 'lsts=[["a","b","c"],["1","2","3"],["x","y","z"]]' 'flattened = []' 'for lst in lsts:' ' flattened.extend(lst)' 100000 loops, best of 3: 2.61 usec per loop Hmm, interestingly, my claim that using .extend is more efficient appears to be false, at least for this example: Morpork:~ repton$ python -m timeit -s 'lsts=[["a","b","c"],["1","2","3"],["x","y","z"]]' 'flattened = []' 'for lst in lsts:' ' flattened = flattened + lst' 100000 loops, best of 3: 2.56 usec per loop (not that there's much in it) -- John. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
