Count Vowels From a String In Python Using Comprehension Method

Counting the number of vowels in a string is a common programming problem that can be solved in various ways. One of the most efficient and concise ways to solve this problem is by using comprehension in Python.

In this blog, we will discuss how to count vowels from a string In Python using the comprehension method. List comprehension is a quick way to create a new list from an existing list or other iterable that allows us to iterate over a sequence, filter out certain elements, and transform the remaining elements into a new list in a single line of code.

We will walk through the step-by-step process of using list comprehension to count the number of vowels in a given string. By the end of this blog, you will have a clear understanding of how to use Python programs to count vowels from a string using the list comprehension method. So, let’s dive in!

What is Comprehension Method in Python?

Comprehension methods in Python are easy and efficient ways of creating data structures such as lists, dictionaries, and sets. They allow you to combine loops and conditional statements into a single line of code, making it easier to create and manipulate data in a more compact and readable manner.

There are three types of comprehension in Python:

  • List Comprehension
  • Dictionary Comprehension
  • Set Comprehension

Python Program to Count Vowels From a String Using Comprehension Method

string = "Python programming"
vowels = "AaEeIiOoUu"
final = [i for i in string if i in vowels]

Code Explanation 

  • Initialization of the string to be checked

First, we create a variable named string and assign the value “Python programming” to it. We create another variable named vowels and assign the value “AaEeIiOoUu” to it. An empty list named ‘final’ is also created to store the vowels found in the string.

  • Using list comprehension to create a list of all vowels present in the string 

Now, we iterate over each character i in the string and check if the current character i is present in the vowels string. If i is a vowel, the program adds it to the final list. 

  • Finding the length of the list ‘final’

Lastly, we print the length of the final list, which represents the count of vowels found in the string using the print(len(final)) command.


The output of the program will be the number of vowels present in the string “Python programming”. In this case, the length of the final list is 4, so the output will be 4.

Another way to count the number of vowels in a string in Python

Some other ways to count the number of vowels in a string in Python are:

  • Using a for loop to iterate over each character in the string.
  • Using the count() method which returns the number of occurrences of a substring within a string. 
  • Using regular expressions to match all the vowels in the string and use the findall() function to find all occurrences.

However, the list comprehension method offers a crisp and efficient way to achieve the desired output. It combines iteration, condition checking, and list creation into a single line of code and allows you to write efficient and readable code by directly expressing the logic.

In this tutorial, we explored how to count the number of vowels in a given string using list comprehension which provides an efficient way to filter and extract specific elements from a string. In this case, we filtered out the vowels from the input string, stored them in a list, and displayed the count. 

By understanding and applying this code, you can enhance your Python programming skills and gain a deeper understanding of list comprehension. It serves as a useful example for handling and processing strings in Python, enabling you to build complex programs that involve text manipulation and analysis.

Some FAQs based on Count Vowels From a String Using Comprehension

Can I extend this program to count consonants as well?

Yes, you can modify the program to count consonants by checking if a character is not in the vowels string and incrementing a counter accordingly.

Does the program consider spaces or punctuation marks as vowels?

No, the program only counts the characters that match the vowels present in the predefined string. Spaces and punctuation marks are not considered vowels.

Can I modify the program to count only unique vowels in a string?

Yes, you can modify the program to count only unique vowels by using a set instead of a list comprehension to store the vowels found.

What happens if the string does not contain any vowels?

If the string does not contain any vowels, the program will return a count of zero.

Is the program case-sensitive?

Yes, the program distinguishes between uppercase and lowercase characters. It counts both uppercase and lowercase vowels separately.

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