Alex Martelli wrote: > <[EMAIL PROTECTED]> wrote: > ... >> In my case of have done os.listdir() on two directories. I want to see >> what files are in directory A that are not in directory B. > > So why would you care about WHERE, in the listdir of B, are to be found > the files that are in A but not B?! You should call .index only if you > CARE about the position. > > def inAnotB(A, B): > inA = os.listdir(A) > inBs = set(os.listdir(B)) > return [f for f in inA if f not in inBs] > > is the "one obvious way to do it" (the set(...) is just a simple and > powerful optimization -- checking membership in a set is roughly O(1), > while checking membership in a list of N items is O(N)...).
And what is the order of passing a list into a set? O(N)+? > > > Alex -- http://mail.python.org/mailman/listinfo/python-list
