How to apply a function on a list of lists two at a time?

Question

I have a list of lists like this:

all_lists = [list0, list1, list2, list3, ....., listn]

And a function like this which takes two arguments from this all_lists.

def function(list0, list1):
    do stuff

The function will keep taking arguments from that all_lists by moving the index by 1 until it reaches to listn.

Is there an efficient way to do that? Thanks!

Answer 1

zip the list with itself and pass arguments in a loop.

for l1, l2 in zip(all_lists[:-1], all_lists[1:]): # or zip(all_lists, all_lists[1:])
    function(l1, l2)

---

MVCE:

lst = [1, 2, 3, 4]

for i, j in zip(lst, lst[1:]):
    print(i, j)

1 2
2 3
3 4

Answer 2

If you want with all possible combination, you can use itertools combination method

>>> import itertools
>>> a = [[1,2],[2,3],[3,4]]
>>> 
>>> for _lst in itertools.combinations(a, 2):
...      print _lst
... 
([1, 2], [2, 3])
([1, 2], [3, 4])
([2, 3], [3, 4])

For your Code:

all_lists = [list0, list1, list2, list3, ....., listn]

for l1,l2 in itertools.combinations(all_list , 2):
    print l1,l2
    # do stuff