With python, how to do looped “unlimited” range indexing?

Question

Having a list or str, like this:

value = 'Water'

Indexing with i=4 value[4] gives me 'r'.

How can i turn my indexing to use larger (unlimited range) values like 16 to get 'r', or 40 for 'W'?

Answer 1

You could use modulus:

>>> value = "Water"
>>> value[16 % len(value)]
'a'
>>> value[40 % len(value)]
'W'

Answer 2

I think you should use remainder operator:

>>> value = 'Water'
>>> value[16%len(value)]
'a'
>>> value[40%len(value)]
'W'

Answer 3

Here is an itertools solution, but it's not pretty...

>>> import itertools
>>> value = 'Water'
>>> next(itertools.islice(itertools.cycle(value), 16))
'a'
>>> next(itertools.islice(itertools.cycle(value), 40))
'W'

itertools.cycle will repeat your input iterable ( 'Water' in this case) infinitely. itertools.islice allows you to slice an iterable as if it were a list . Calling next once just returns the first value from the slice.