Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Python Collections (Retired) Lists Redux Disemvoweled

Pushkar Kadam
Pushkar Kadam
3,823 Points
Posted by Pushkar Kadam
Pushkar Kadam
3,823 Points

'treehouse' is giving me back 'trhuse' and how does try and except work?

I wrote a simple code to get an input from the user and remove the vowels. When I type 'apple', the output is 'ppl'. But, when I type, 'treehouse', it gives me 'trhuse'. My observation shows that if a character is repeated more than 3 times, the 3rd time is not removed. But, why wasn't 'u' removed from 'treehouse'. I tried three types of codes.

vowels = list('aeiou')

the_word = input("Enter a word. \n>")
word_list = list(the_word)

for letter in word_list:
    if letter in vowels:
        word_list.remove(letter)
print("".join(word_list))

Also, this code

the_word = input("Enter a word: \n>")
word_list = list(the_word)

for letter in word_list:
    if letter == 'a':
        word_list.remove('a')
        continue
    elif letter == 'e':
        word_list.remove('e')
        continue
    elif letter == 'i':
        word_list.remove('i')
        continue
    elif letter == 'o':
        word_list.remove('o')
        continue
    elif letter == 'u':
        word_list.remove('u')
        continue
print("".join(word_list))

Both the above code gives me :'apple' gives back 'ppl' but, 'treehouse' gives 'trhuse' But, when I used the code with try and except, my problem was solved. So, how does try and except works in determining the elimination of all the vowels.

vowels = list('aeiou')

the_word = input("Enter a word. \n>")
word_list = list(the_word)

for letter in word_list:
    for letter in vowels:
        while True:
            try:
                word_list.remove(letter)
            except:
                break

print("".join(word_list))

The last code works and 'treehouse' gives me back 'trhs'

1 Answer

Steven Parker
Steven Parker
231,236 Points
Steven Parker
Steven Parker
231,236 Points

:point_right: Never modify a list while it is being used for loop iteration.

It can cause items to be skipped and/or the loop may end early.

If you intend to modify a list in a loop, iterate using a copy of the list:

for letter in word_list[:]:  # using splice to make a copy
john larson
john larson
16,594 Points

This code works, but isn't it still iterating and modiying in the try block?

# string of vowels saved as a list
vowels = list('aeiou')
# asks for user input
the_word = input("Enter a word. \n:> ")
# transorm the user input into a list
word_list = list(the_word)
# iterate word_list
for letter in word_list:
# iterate vowels
    for letter in vowels:
# as long as there are vowels
        while True:
# check for vowels
            try:
                word_list.remove(letter)
            except:
# if theres no vowel
                break

print("".join(word_list))