[FIXED] Error in python code (IndexError: list assignment index out of range) Beginner level

Issue

While running the following code

names = ["Joey Tribbiani", "Monica Geller", "Chandler Bing", "Phoebe Buffay"]
usernames = []

# write your for loop here
for index in range(len(names)):
    usernames[index] = names[index].lower().replace(" ", "_")


print(usernames)

this error is observed

Traceback (most recent call last):
  File "vm_main3.py", line 47, in <module>
    import main
  File "/tmp/vmuser_kncqjadnfl/main.py", line 2, in <module>
    import studentMain
  File "/tmp/vmuser_kncqjadnfl/studentMain.py", line 1, in <module>
    import usernames
  File "/tmp/vmuser_kncqjadnfl/usernames.py", line 6, in <module>
    usernames[index] = names[index].lower().replace(" ", "_")
IndexError: list assignment index out of range

any help will be appreciated.

Solution

Most errors speak for themselves.

Your list usernames is initialized as empty, that is, of length 0. So whatever integer index is, usernames[index] will try to access a nonexistent element. That's why you get an IndexError.

What you want to do is to append elements to a list usernames. append method does that. So your for-loop should read:

for index in range(len(names)):
    usernames.append(names[index].lower().replace(" ", "_"))

Try reading any python-beginner's tutorial about lists, or at least the official documentation before proceeding.

Answered By - Ignatius