CODEWITHSUNDEEP
python
user3444987
user3444987

Reputation: 11

Anti-Vowel program Issue

def anti_vowel(text):
    new = ''
    for char in text:
        if char in "aeiou" or char in "AEIOU":
            ala = text.replace(char, '')
    new = new + ala
    return new
print anti_vowel("Hey look Words!")

It returns 'Hey lk Wrds!' which means that the function somehow completely overlooked the "e".

Upvotes: 1

Views: 4634

Answers (4)

ajay
ajay

Reputation: 9680

Strings are immutable in Python. So when you do the following,

ala = text.replace(char, '')

this create a new string replacing char with empty string and assigns it to ala. However, the value of text is still the same original string the function anti_vowel was passed. After the loop terminates, value of ala will be the original string with all occurrences of the last vowel removed. What you should do instead is - 

def anti_vowel(text):
    for char in text:
        if char in "aeiouAEIOU":
            # update text after replacing all instances of the vowel
            # char in text with the empty string
            text = text.replace(char, '')
    return text

You might also consider using the string method translate. 

def anti_vowel(text):
    vowels = "aeiouAEIOU"
    return text.translate(None, vowels)

Upvotes: 0

Hugh Bothwell
Hugh Bothwell

Reputation: 56624

def anti_vowel(text):
    new = ''
    for char in text:
        if char in "aeiou" or char in "AEIOU":
            ala = text.replace(char, '')

Let's stop here and look at what happens:

For each character in the message, if the character is a vowel, you make a copy of the original text with that vowel removed. Then you assign it to ala... but?

    new = new + ala
    return new

The indentation means that new = new + ala only runs once - after your for loop is finished. On your sample data, "Hey look Words!", the last vowel you saw was 'o', so ala contains a string with no 'o's (but all other vowels left alone):

print anti_vowel("Hey look Words!")   # => "Hey lk Wrds!"
print anti_vowel("aeiouAEIOU!")       # => "aeiouAEIO!"

(Your test string only had two vowel-characters, 'e' and 'o', which meant you couldn't see any difference between "why is the e not removed?" and "why is only the o removed?", which would have been a more obvious indicator of the problem!)

Fixing your code directly would look like

def anti_vowel(text):
    result = text
    for char in text:
        if char in "aeiouAEIOU":
            result = result.replace(char, '')
    return result

but a more Pythonic approach is:

# a set allows very fast look-ups
VOWELS = set("aeiouAEIOU")

def no_vowels(s):
    # keep every character that is not a vowel
    return "".join(ch for ch in s if ch not in VOWELS)

print(no_vowels("Look Ma, no vowels!"))  # => "Lk M, n vwls!"

Upvotes: 6

elixenide
elixenide

Reputation: 44823

The problem is that you are doing the replace on text every time, not on the updated variable ala. Try this instead:

def anti_vowel(text):
    new = ''
    ala = text
    for char in text:
        if char in "aeiou" or char in "AEIOU":
            ala = ala.replace(char, '')
    new = new + ala
    return new
print anti_vowel("Hey look Words!")

Upvotes: 1

Christian Tapia
Christian Tapia

Reputation: 34146

You can instead check if char is not a vowel. If it is not, then add it to the string:

def anti_vowel(text):
    new = ''
    for char in text:
        if char not in "aeiouAEIOU":
            new += char
    return new

Note that it would be better to use

if char not in "aeiouAEIOU":

or (as @Michal commented):

 if char.lower not in "aeiou":

instead of

if char not in "aeiou" and char not in "AEIOU":

Upvotes: 1

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