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Python Python Collections (2016, retired 2019) Lists Disemvowel

Posted by Odane Williams
Odane Williams
Courses Plus Student 6,634 Points

Can't spot why the for loop isn't appending to the list.

The script supposed to iterate through word and append each individual letter in to my_list. Then after that all the vowels are removed, and then the word returned as a whole string using the .join method.

disemvowel.py 
def disemvowel(word):
    word_list = []
    word.lower()
    for letter in word:
        word_list.append(letter)
    word_list.remove("a")
    word_list.remove("e")
    word_list.remove("i")
    word_list.remove("o")
    word_list.remove("u")
    word = ''.join(word_list)
    return word

1 Answer

Riki Montgomery
Riki Montgomery
9,803 Points
Riki Montgomery
Riki Montgomery
9,803 Points

Your loop is getting to word_list.remove("a") and then stopping, because word_list is empty. You can't remove something that's not there.

Odane Williams
Odane Williams
Courses Plus Student 6,634 Points

How is it getting to it if it's not in the same block?

Riki Montgomery
Riki Montgomery
9,803 Points

This will help you see what's happening: http://www.pythontutor.com/

  • Click on Start visualizing your code now
  • Make sure you're writing your code in Python 3.6 in the dropdown.
  • Write your expression in the box, like this(don't for get to call it on the bottom, like I did):
def disemvowel(word):
    word_list = []
    word.lower()
    for letter in word:
        word_list.append(letter)
    word_list.remove("a")
    word_list.remove("e")
    word_list.remove("i")
    word_list.remove("o")
    word_list.remove("u")
    word = ''.join(word_list)
    return word

disemvowel("Word")
  • Then click visualize execution.
  • Use the forward and back buttons to see how the computer reads your code IRL.

I don't know python very well, but that will help you understand how you wrote your function wrong and how you might fix it.

You'll notice that word.lower() doesn't seem to be doing anything either.

Riki Montgomery
Riki Montgomery
9,803 Points

I misspoke. word_list is not empty. It's just that "a" isn't in there, so it stops the function at word_list.remove("a"). I'm not sure why. Try out pythontutor and mess around with different ways of writing this.

Riki Montgomery
Riki Montgomery
9,803 Points

This works in http://www.pythontutor.com but it breaks when you add the rest of the characters to be removed.

def disemvowel(word):
    word_list = []
    for letter in word:
        word_list.append(letter)
    word_list.remove("o")
    new_word = ''.join(word_list)
    return new_word

disemvowel("Word")