Function to remove vowels from string does not work if vowels appear consecutively

Question

def disemvowel(string):
    vowels = ('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U')
    listString = list(string)
    for t in listString:
        if t in vowels:
            listString.remove(t)
    string = ''.join(listString)
    return string

The function is supposed to remove all the vowels and if the input is:

'This website is for losers LOL!'

The correct output should be:

'Ths wbst s fr lsrs LL!'

But the moment I changed the input to have vowels appear consecutively with each other i.e.

'This websitea is for loosers LOL!'

The output becomes

'Ths wbsta s fr losrs LL!'

which is incorrect (see 'wbsta' and 'losrs').

why not a regex replace like `re.sub("[aeiou]","",string,flags=re.I)` — Jean-François Fabre, Aug 29 '17 at 15:27

score 4 · Answer 1 · answered Aug 29 '17 at 15:28

4

Instead of removing the vowels, why not just construct the string from the characters that aren't vowels?

return ''.join([c for c in string if c not in vowels])

answered Aug 29 '17 at 15:28

Mureinik

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Wouldn't a generator be preferable over a list comprehension? – Alexander Aug 29 '17 at 15:36
1

No for `join` a list comprehension is better because [`str.join` requires a sequence](https://github.com/python/cpython/blob/v3.6.2/Objects/unicodeobject.c#L9903) and would immediately convert it to a list (additional overhead) if it's not a sequence. – MSeifert Aug 29 '17 at 15:37
1

To add to @MSeifert comment, this is because behind the scenes, `str.join` converts the iterator passed in to a list. Passing in a generator would just create additional overhead. If your curious, the implementation details can be seen [here](https://github.com/python/cpython/blob/master/Objects/stringlib/join.h#L22). – Christian Dean Aug 29 '17 at 15:38

score 1 · Answer 2 · edited Aug 30 '17 at 07:56

It's generally not a good idea to remove items from the thing you're iterating from, because this can cause implications during the iteration. Therefore, instead of removing the characters that are vowels from the string, instead add the characters that aren't vowels to a new string.

def disemvowel(string):
    vowels = ('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U')
    listString = list(string)
    string = ""
    for t in listString
        if t not in listString
            string += t

    return string

Function to remove vowels from string does not work if vowels appear consecutively

2 Answers2