In article <535c67e9$0$29965$c3e8da3$54964...@news.astraweb.com>, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote:
> I think the two obviously good enough approaches are: > > - save a "to be deleted" list, then delete those keys; > > - copy the "not to be deleted" items into a new dict There is a third possibility: Iterate over the dict, storing keys to be deleted in a list, but break out after the list reaches N items. Delete those keys from the dict. Repeat the whole process until you reach the end of the dictionary before you reach N saved keys. It's going to take multiple (perhaps many) passes over the dict, but it will limit the amount of extra memory used. In the extreme case, if N=1, with k keys in the dict, it will turn a process which is O(k) in time and O(k) in extra memory into one which is O(k^2) in time and O(1) in extra memory. Is that a good tradeoff? Only your hairdresser knows for sure. -- https://mail.python.org/mailman/listinfo/python-list
