"Pawe³ Sakowski" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] Tom Anderson wrote: > def flatten(ll): > return reduce(lambda a, l: a.extend(l), ll, []) > > How would one do that as a list comp, by the way? I'm really not very > good > with them yet.
Not really a list-comprehension based solution, but I think what you want is >>> ll=[[1,2],[3,4,5],[6]] >>> sum(ll,[]) [1, 2, 3, 4, 5, 6] Unless sum knows to typecheck input items and special-case lists and use list.extend rather than list+list, this turns an O(n) operation into an O(n**2) operation. Sum is meant for numbers. Terry J. Reedy
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