I would like to iterate through a list of strings and replace each instance of a character ('1', for example) with a word. I am confused why this would not work.
for x in list_of_strings:
x.replace('1', 'Ace')
Side note, the strings within the lists are multiple characters long. ('1 of Spades)
You can use a list comprehension:
list_of_strings = [x.replace('1', 'Ace') for x in list_of_strings]
This is natural in Python. There is no significant benefit in changing your original list directly; both methods will have O(n) time complexity.
The reason your code does not work is str.replace does not work in place. It returns a copy, as mentioned in the docs. You can iterate over a range object to modify your list:
for i in range(len(list_of_strings)):
list_of_strings[i] = list_of_strings[i].replace('1', 'Ace')
Or use enumerate:
for idx, value in enumerate(list_of_strings):
list_of_strings[idx] = value.replace('1', 'Ace')
enumerate, in my opinion.