Rhamphoryncus schrieb: >> This is different from the other approaches in that it doesn't >> modify items. If you wanted a new list, you could incrementally >> build one already in the first pass, no need to collect the >> indices first (as BlackJack explains). > > I didn't feel this distinction was worth mentioning, since "oldlist[:] > = newlist" is so trivial. The only solution that really avoids making > a copy is the reverse-iteration one.
The distinction is relevant for performance, as the slice assignment has a complexity linear with the number of elements. Whether making a copy is expensive depends on the precise data: the solution that makes the copy in reverse may have quadratic complexity (if the number of removed elements increases with the list size); the version that appends all remaining elements to a new list and then does slice assignment should behave better-than-quadratic (in recent versions, it should give you linear performance). Regards, Martin -- http://mail.python.org/mailman/listinfo/python-list
