how to loop with multiple index in Python

Question

I have to write a loop which is very simple in languages like java and c.

for (int i = 0; i <arr.length()-1; i++) {
   for (int j = i+1; j <arr.length(); j++) {
      //process
   }
}

But I can't get to mimic this in Python. For example:

for number in arr:
    print(number)

But how to iterate with the i and j indices.

Answer 1

ll = len(arr)

for i in range(ll):
    for j in range(i+1, ll, 1):
        # process

Answer 2

Use a nested loop, the same as you would in another language:

for i in range(len(arr)-1):
    for j in range(i, len(arr))::
        print(arr[j])

or:

for i in range(len(arr)-1):
    for number in arr[i:]:
        print(number)

or perhaps:

for i, n1 in enumerate(arr[:-1]):
    for j, n2 in enumerate(arr[i:], i):
        print(f"arr[{i}] = {n1}, arr[{j}] = {n2}")

depending on whether your processing needs to operate on the elements themselves, the indices, and/or both.