How can I create a list with all the possible combinations of common letters between two strings?

Question

I have tried using set() , as it will print only unique elements of both sets. In my code, common_letters is the set of common letters from both strings. I'm trying to print all the possible combinations of words which can be generated from the elements of common_letters and also trying to convert that word list into one where the first letter of each string is capitalized.

This is my code so far:

import itertools as itr

def listtostring(s):
    string =" "
    return (string.join(s))

str1=input("Enter 1st string:")
str2=input("Enter 2nd string:")
common_letters=set(set(str1) & set(str2))

for letter in common_letters:
    common_letters.add(letter)
print("list of common letters : ",common_letters)

mylist=list(itr.permutations(common_letters))

print("Words generated from common letters are : ",listtostring(mylist))

I am getting the following error however:

File "C:/Users/problem_1.py", line 18, in <module>
    print("Words generated from common letters are : ",listtostring(mylist))

File "C:/Users/problem_1.py", line 5, in listtostring
    return (string.join(s))

TypeError sequence item 0: expected str instance, tuple found

The expected output should be all combinations of common letters forming words (as String type) with first letter in uppercase.

Answer 1

You are using your listtostring function wrong, you should use that on every permutation created, not on the whole list of permutations. And you can use capitalize() to capitalize the first letters.

Here is the modified code, I removed your for loop as it wasn't doing anything:

import itertools as itr

def listtostring(s):
    string = ""
    return (string.join(s))

str1=input("Enter 1st string:")
str2=input("Enter 2nd string:")
common_letters=set(set(str1) & set(str2))
print("list of common letters : ",common_letters)

mylist=list(itr.permutations(common_letters))
finalList = [listtostring(x).capitalize() for x in mylist]

print("Words generated from common letters are : ", finalList)

You can change the last line to the following if you want it to all be one string:

print("Words generated from common letters are : ", " ".join(finalList))