python remove() function not working

Question

learning Python, and for some reason I can't get the python remove function to work. It works when I'm testing it interactively in Python in the console but not when I write a script. Please help me out! it turns the input into a list but doesn't remove the vowels.

print("\nVowel Removal")
print("Enter a word to have the vowel removed.")
word_input = input("> ")
word_input = list(word_input)

vowels = list('aeiou')
output = []

while True:
    try:
        word_input.remove(vowels)
    except:
        print("You must enter a word.")
        break

print(word_input)

"It works when I'm testing it interactively in Python in the console but not when I write a script." But how are you testing it in the Python console? — user707650
– user707650, Commented Jun 24, 2015 at 7:26
word_input = list(word_input) vowels = list('aeiou') word_input.remove(vowels) this have no sense. what exactly you try to remove? — Andersson
– Andersson, Commented Jun 24, 2015 at 7:29

Bakuriu · Accepted Answer · 2015-06-24 07:30:39Z

Here you have:

word_input = list(word_input)

So word_input is a list of strings (in particular of characters). vowels is:

vowels = list('aeiou')

i.e. an other list of strings.

You do:

word_input.remove(vowels)

which always fails because vowels is a list of strings and word_input only contains strings. remove removes a single element. It does not remove all elements contained in the argument. See the error message:

In [1]: vowels = list('aeiou')

In [2]: vowels.remove(vowels)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-2-6dd10b35de83> in <module>()
----> 1 vowels.remove(vowels)

ValueError: list.remove(x): x not in list

Note that it says: list.remove(x): x not in list so the argument to remove should be an element of the list, not a list of elements to remove.

You have to do:

for vowel in vowels:
    word_input.remove(vowel)

to remove all vowels. Moreover remove only removes the first occurrence of the element, so you may have to repeatedly call remove to remove all occurrences of a vowel.

Note: to remove vowels from a string you could simply use:

the_string.translate(dict.fromkeys(map(ord, vowels)))

as in:

In [1]: the_string = 'Here is some text with vowels'
   ...: vowels = 'aeiou'
   ...: 

In [2]: the_string.translate(dict.fromkeys(map(ord, vowels)))
Out[2]: 'Hr s sm txt wth vwls'

Or if you want to use those lists:

result = []
# vowels = set('aeiou') may be faster than using a list
for char in word_input:
    if char not in vowels:
        result.append(char)

thank you for the great answer! I will accept it as the correct answer in a couple of minutes when it lets me. Thank you!

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