Force all iterations on an iterable

Question

I\'ve written a for-loop using map, with a function that has a side-effect. Here\'s a minimal working example of what I mean:

def someFunc(t):
    n, d = t
    d         


        

Answer 1

You don't want to do this (run a map() just for the side effects), but there is a itertools consume recipe that applies here:

from collections import deque

deque(map(somefunc, ((i,d) for i in range(10**3))), maxlen=0)

The collections.deque() object, configured to a maximum size of 0, consumes the map() iterable with no additional memory use. The deque object is specifically optimized for this use-case.