Teaching Kids Programming – Remove Vowels from a String

Teaching Kids Programming: Videos on Data Structures and Algorithms

Given a string s, remove the vowels ‘a’, ‘e’, ‘i’, ‘o’, and ‘u’ from it, and return the new string.

Example 1:
Input: s = “leetcodeisacommunityforcoders”
Output: “ltcdscmmntyfrcdrs”

Example 2:
Input: s = “aeiou”
Output: “”

Constraints:
1 <= s.length <= 1000
s consists of only lowercase English letters.

How to erase vowels in a string?
Loop over the string and check every character, if it is a vowel ignore it otherwise add it to the answer.

Python’s Function to Remove Vowels from a String

Let’s iterate each character and add it if it isn’t a vowel.

class Solution:
    def removeVowels(self, s: str) -> str:
        ans = ""
        for i in s:
            if i not in "aeiou":
                ans += i
        return ans

class Solution:
    def removeVowels(self, s: str) -> str:
        ans = ""
        for i in s:
            if i not in "aeiou":
                ans += i
        return ans

Let’s use a list and then join them:

class Solution:
    def removeVowels(self, s: str) -> str:
        ans = []
        for i in s:
            if i not in "aeiou":
                ans.append(i)
        return "".join(ans)

class Solution:
    def removeVowels(self, s: str) -> str:
        ans = []
        for i in s:
            if i not in "aeiou":
                ans.append(i)
        return "".join(ans)

We could define the vowels as a set so the lookup time is faster:

class Solution:
    def removeVowels(self, s: str) -> str:
        ans = []
        vowels = set("aeiou")
        for i in s:
            if i not in vowels:
                ans.append(i)
        return "".join(ans)

class Solution:
    def removeVowels(self, s: str) -> str:
        ans = []
        vowels = set("aeiou")
        for i in s:
            if i not in vowels:
                ans.append(i)
        return "".join(ans)

We can use Regex Expression:

1
2
3

class Solution:
    def removeVowels(self, s: str) -> str:
        return re.sub('a|e|i|o|u', '', s)

class Solution:
    def removeVowels(self, s: str) -> str:
        return re.sub('a|e|i|o|u', '', s)

Or we can remove each vowel one by one:

class Solution:
    def removeVowels(self, s: str) -> str:
        for i in "aeiou":
            s = s.replace(i, "")
        return s

class Solution:
    def removeVowels(self, s: str) -> str:
        for i in "aeiou":
            s = s.replace(i, "")
        return s

And we can use the list comprehension:

1
2
3

class Solution:
    def removeVowels(self, s: str) -> str:
        return "".join([c for c in s if c not in "aeiou"])

class Solution:
    def removeVowels(self, s: str) -> str:
        return "".join([c for c in s if c not in "aeiou"])

Using filter and lambda function to remove the vowels from a string in Python:

1
2
3

class Solution:
    def removeVowels(self, s: str) -> str:
        return "".join(filter(lambda x: x not in "aeiou", s))

class Solution:
    def removeVowels(self, s: str) -> str:
        return "".join(filter(lambda x: x not in "aeiou", s))

–EOF (The Ultimate Computing & Technology Blog) —

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Python’s Function to Remove Vowels from a String

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