Yet another solution to this problem. I needed a solution that is as fast as possible. That means only one iteration over the list and preferably O(1) for adding data to one of the resulting lists. This is very similar to the solution provided by sastanin, except much shorter:
from collections import dequedef split(iterable, function): dq_true = deque() dq_false = deque() # deque - the fastest way to consume an iterator and append items deque(( (dq_true if function(item) else dq_false).append(item) for item in iterable ), maxlen=0) return dq_true, dq_falseThen, you can use the function in the following way:
lower, higher = split([0,1,2,3,4,5,6,7,8,9], lambda x: x < 5)selected, other = split([0,1,2,3,4,5,6,7,8,9], lambda x: x in {0,4,9})If you're not fine with the resulting deque object, you can easily convert it to list, set, whatever you like (for example list(lower)). The conversion is much faster, that construction of the lists directly.
This methods keeps order of the items, as well as any duplicates.