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Python Python Collections (2016, retired 2019) Lists Disemvowel

yannis sousanis
yannis sousanis
7,199 Points
Posted by yannis sousanis
yannis sousanis
7,199 Points

need help for this list problem

I tried to run this on my IDE and it works. But it doesn't work here

disemvowel.py 
def disemvowel(word):

    word_list = list(word)

    for i in word_list:
        try:
            word_list.remove("a")
        except ValueError :
            break
    for i in word_list:
        try:
            word_list.remove("e")
        except ValueError :
            break        
    for i in word_list:
        try:
            word_list.remove("i")
        except ValueError :
            break    
    for i in word_list:
        try:
            word_list.remove("o")
        except ValueError :
            break
    for i in word_list:
        try:
            word_list.remove("u")
        except ValueError :
            break
    for i in word_list:
        try:
            word_list.remove("A")
        except ValueError :
            break
    for i in word_list:
        try:
            word_list.remove("E")
        except ValueError :
            break        
    for i in word_list:
        try:
            word_list.remove("I")
        except ValueError :
            break    
    for i in word_list:
        try:
            word_list.remove("O")
        except ValueError :
            break
    for i in word_list:
        try:
            word_list.remove("U")
        except ValueError :
            break       

    word = str(word_list)
    return word

1 Answer

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi there,

That's a serious effort! Lots of lines! Good work.

There's a simpler way to do this - while we could look at why your code doesn't work, there's a principle that it breaches, Don't Repeat Yourself. Your code loops over the list for every letter, lowercase and uppercase. That's not best practice.

How about we start with a list of the vowels in lower case:

vowels = ['a', 'e', 'i', 'o', 'u']

We also want to build up a string to return out of the function rather than using what's passed in. Let initialize this to an empty string too:

    vowels = ['a', 'e', 'i', 'o', 'u']
    output = ""

Now, we can loop through the word parameter - something you're very familiar with! - and see if each character is in the list of vowels. 

for letter in word:
    # test letter

If it is, do nothing, if it isn't add that letter to the output string. We can test if a letter is in a list with the keyword in:

if letter in vowels:
    # do something

But here we actually want to do something is the letter is not in the list. We can use not in for this. 

if letter not in vowels:
   # do something

So, loop through the word and test each letter to see if it is not in the list of vowels. If that's the case, add it to output else move on; do nothing - we don't need an else clause.

This doesn't pick up on uppercase/lowercase, though. So, we can lowercase the test only. The list is all lowercase, so we just need to ensure we use .lower() on letter. That way, we don't change letter to lowercase.

Something like:

def disemvowel(word):
    vowels = ['a', 'e', 'i', 'o', 'u']
    output = ""
    for letter in word:
        if letter.lower() not in vowels:
            output += letter
    return output

I hope that explanation makes sense. That's one solution to the problem, I am sure there are many others that are equally correct, if not better.

Steve.