How to make a list start-end connected?

Question

I have this list:

l = [0, 1, 2]

and obviously l[0] = 0, l[1] = 1, l[2] = 2,
but I want l[3] to be = to 0, l[4] = 1, l[5] = 2 and so on...

Do you need to access the non-existing indexes directly, or you want to iterate over the list indefinitely? See https://stackoverflow.com/q/23416381/476… — deceze, Jul 17 '20 at 09:57
What problem do you hope to solve by doing this? The best approach depends on why you want this behaviour. — Karl Knechtel, Jul 17 '20 at 10:01

Vishal Singh · Answer 1 · 2020-07-17T10:36:20.590

1

you can use the modulus operator to cycle through the elements of the list.

l[index % 3]

In general:

lst = [0, 1, 2]

lst[index % len(lst)]

edited Jul 17 '20 at 10:36

answered Jul 17 '20 at 10:00

Vishal Singh

6,014
2
17
33

score 0 · Answer 2 · answered Jul 17 '20 at 09:57

Depending on what you're trying to do, you can "multiply" a list to create a longer, repeating list of the original. Alternatively, you can create an iterator that just yields the same sequence of numbers indefinitely:

>>> numbers = [0, 1, 2] * 5
>>> numbers
[0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 2]
>>> from itertools import cycle
>>> number_iter = cycle([0, 1, 2])
>>> next(number_iter)
0
>>> next(number_iter)
1
>>> next(number_iter)
2
>>> next(number_iter)
0
>>> next(number_iter)
1
>>> next(number_iter)
2
>>>

How to make a list start-end connected?

2 Answers2