使用 Python3 itertools 排列：如何指定所有 r > 1

Question

I only want the permutations of a string that are of size 2 or more, so no empty set or set of one character. It seems r must be an int and I cannot say r = range(2,N) or r>=2 . The only solution I can think of is a for-loop; is there a better way?

Answer 1

You do need a for loop. But you could do it more succinctly with itertools.chain , which would create a generator that yields first all permutations of length 2, then 3, etc.

from itertools import chain, permutations

lst = [1, 2, 3]
tuples_gen = chain(*(permutations(lst, i) for i in range(2, len(lst) + 1)))