Reverse each word except punctuation(s) without altering their position - Python3

Question

I am trying to solve a problem with the below #PROBLEM DEFINITION -

1. Reverse each word in the input string.
2. The order of the words will be unchanged.
3. A word is made up of letters and/or numbers.
4. Other characters (spaces, punctuation) will not be reversed.

However, I am not able to satisfy the requirement of keeping the order enacted. Below is my code. Any help would be appreciated.

Provided: input string = 'Hello! cu2 Ayaan...'

Expected: output string = 'olleH! 2uc naayA...'

def swap(a, b):
    return b, a

def reverse_each_word(sentence):
    list_of_string = [i for i in sentence]
    r = len(list_of_string) - 1
    l = 0
    while l < r:
        if not list_of_string[l].isalpha():
            l += 1
        elif not list_of_string[r].isalpha():
            r -= 1
        else:
            list_of_string[l], list_of_string[r] = swap(list_of_string[l], list_of_string[r])
            l += 1 
            r -= 1
    result = "".join(list_of_string)
    return result

Answer 1

Good effort. You are almost there. Congrats. I did minimal changes in your code. All I did is I split up the sentence into words (and then split each character of the word) and applied your reversal logic to every split word-list. There was also a check missing ..isdigit() since as per prerequisite 3 a word can be composed of alphabets as well as a digit. That's all. Rest is your code.

I have assumed that words are separated by 1 and only 1 blank spaces. If not please use re module.

Below is the code. If you don't understand anything, please ask.

def swap(a, b):
    return b, a

def reverse_each_word(sentence):
    list_of_string = [i for i in sentence.split(" ")]
    Finalresult = ""
    for eachString in list_of_string:
        eachString = [x for x in eachString]
        r = len(eachString) - 1
        l = 0
        while l < r:
            if not (eachString[l].isalpha() or eachString[l].isdigit()):
                l += 1
            elif not (eachString[r].isalpha() or eachString[r].isdigit()):
                r -= 1
            else:
                eachString[l], eachString[r] = swap(eachString[l], eachString[r])
                l += 1 
                r -= 1
        result = "".join(eachString)
        Finalresult += (result+" ")
    return Finalresult

print(reverse_each_word( 'Hello! cu2 Ayaan...'))

The output is

olleH! 2uc naayA...