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Python Python Collections (2016, retired 2019) Lists Disemvowel

Posted by Li Zhang Tan
Li Zhang Tan
1,396 Points

This disemvowel function works in the Python workspace but isn't accepted in the Code Challenge?

I don't know what's wrong with it. :(

disemvowel.py 
vowels = ["a", "e", "i", "o", "u"]

def disemvowel(word):
    listed = list(word)
    for letter in listed:
        if letter.lower() in vowels:
            listed.remove(letter)
        else:
            pass
    word = "".join(listed)
    return word

3 Answers

Charlie Gallentine
Charlie Gallentine
12,092 Points
Charlie Gallentine
Charlie Gallentine
12,092 Points

As the loop runs, it alters the size of the list it is working on. I would recommend declaring a new empty list before the loop and putting letters into it which are not vowels. Thus the original list is unaltered and the new one which is only consonants can be returned.

SPOILER 

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

def disemvowel(word):
    listed = list(word)
    new_list = [] # A new list where consonants can go
    for letter in listed:
        if letter.lower() not in vowels:
            new_list.append(letter) # Adds letter to new_list if it is a consonant, does nothing if vowel

    word = "".join(new_list)
    return word
Li Zhang Tan
Li Zhang Tan
1,396 Points

Sooo from what you're saying, the FOR loop, when applied to the list, doesn't remember which item it was performing the command on, instead, it remembers the position of the item it performs the command on. Which is why, when a vowel is removed from the list, the other letters shift positions, but the command doesn't realise it. Am I understanding this right?

William Harrison
William Harrison
9,585 Points
William Harrison
William Harrison
9,585 Points

You are changing the size of your loop as you remove letters. If there is several vowels in a row some are missed.

Charlie Gallentine
Charlie Gallentine
12,092 Points
Charlie Gallentine
Charlie Gallentine
12,092 Points

I believe that to be right. It is my understanding that in a for loop, the condition is 

for [iterating piece starting with first index (0)] in [something which is iterable]:
    ......

By having two vowels next to each other, I think it iterates over the first one, for example the 'e' at index 2 in "Cheese", removes it, and the string becomes "Chese". The for loop has already iterated over index 2, so it moves on to index 3. With vowels next to each other, the program will miss every other one. The iterating piece of the for loop is just the name given to the incrementer.