How to create a chaining or cyclic sequence with a list in Python, so that after the last index of a-CodePudding

I have an alphabets list:

alpha_list = ['a', 'b', 'c', 'd', 'e']

For a given alphabet(considering it will always be present in alpha_list) I want to get an alphabet whose index is garter by a given number, consider below function for example:

def get_replacing_letter(alphabet, number):
    index = alpha_list.index(alphabet)
    return alpha_list[index   number]

get_replacing_letter('a', 2) will give me 'c'

what I want is get_replacing_letter('d', 2) should give 'a' similarly get_replacing_letter('e', 2) should give 'b'

So the alph_list should work in a chaining sequence or cyclic manner. I am wondering how to achieve this in Python?

CodePudding user response：

You can make new index take the modulo of the length of the list:

return alpha_list[(index   number) % len(alpha_list)]

CodePudding user response：

At the moment I achieved it by extending the alpha_list with itself:

alpha_list.extend(alpha_list)

This way as index method gives first index of occurance, I could manage to get it working.

However I am wondering if there is any better way to achieve this.