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Python Python Collections (2016, retired 2019) Lists Disemvowel

Posted by Vincent Nguyen
Vincent Nguyen
4,520 Points

Could someone help me with this?

I need to remove vowels from a word but im not sure how to do it

disemvowel.py 
def disemvowel(word):
    word = input("What would you like to de-vowel?  ")
    disemvowel = word.remove('a','A','e','E','i','I','o','O','u','U')
print(disemvowel)

1 Answer

Alex Wootton
PLUS
Alex Wootton
Courses Plus Student 5,943 Points
Alex Wootton
Alex Wootton
Courses Plus Student 5,943 Points

I went with the following solution personally:

  1. Create a list of vowels to match the letters in our word against
  2. Convert our word string into a list so that we can use remove() on it
  3. Start a for loop that iterates through a copy of the letters list (this is important, I'll explain at the end)
  4. Check to see if the current letter is in the vowels list in it's lowercase form
  5. If it is, use remove() to remove the current letter from letters list. Remember that it only removes the first match that it finds
  6. Once each letter in letters has been checked, join each item in the letters list into a single string
  7. return the string. It is important to return and not print so that the output can be handed back to it's caller. Some great explanations and examples can be found here

The code will look something like this:

def disemvowel(word):
    vowels = ["a","e","i","o","u"] # a list of vowels to compare our letters against
    letters = list(word)
    for letter in letters.copy():
        if letter.lower() in vowels:
            letters.remove(letter)
    word = "".join(letters)
    return word

As promised, the reason we iterate through the letters list backwards is to ensure that we don't accidentally skip letters by changing their indexes in the list. Here is some code to demonstrate:

A list is indexed from left to right, starting at zero. So if we take the string "aid" for example, once split into a list we have something that looks like this:

["a","i","d"]

With "a" at index 0, "i" at index 1 and "d" at index 2

If we were to iterate through the list starting at 0, we would check "a" against our vowels, match it, remove it and then move on to the next item. However, because we have removed "a", "i" is now the first item in the list and has assumed the index of 0 and following suite "d" is now at index 1. The for loop continues on and checks the item at index 1 so "d" is checked, not found in the list of vowels and the loop ends as there are no more items in the list to iterate through. As you might have spotted, "i" was never checked and as such is returned along with "d" when the function ends.

To prevent this from happening we can simply use a copy of the letters list that does not change when we remove items from our original.

I hope this helps!

Vincent Nguyen
Vincent Nguyen
4,520 Points

Thank you for helping! It helped a lot :)