Using Set() in Python Pangram Checking

Given a string check if it is Pangram or not. A pangram is a sentence containing every letter in the English Alphabet. Lowercase and Uppercase are considered the same. Examples:

Input : str = 'The quick brown fox jumps over 
               the lazy dog'
Output : Yes
// Contains all the characters from ‘a’ to ‘z’

Input : str='The quick brown fox jumps over the dog'
Output : No
// Doesn’t contains all the characters from ‘a’
// to ‘z’, as ‘l’, ‘z’, ‘y’ are missing

This problem has existing solution please refer Pangram Checking link. We will solve this in Python using Set() data structure and List() comprehension. Approach is very simple,

1. Convert complete sentence in lower case using lower() method of string data type in python.
2. Now pass this sentence into Set(str) so that we could have list of all unique characters present in given string.
3. Now separate out list of all alphabets (a-z), if length of list is 26 that means all characters are present and sentence is Pangram otherwise not.

Implementation:

Python3

# function to check pangram

def pangram(input):

    # convert input string into lower case
    input = input.lower()

    # convert input string into Set() so that we will
    # list of all unique characters present in sentence
    input = set(input)

    # separate out all alphabets
    # ord(ch) returns ascii value of character
    alpha = [ ch for ch in input if ord(ch) in range(ord('a'), ord('z')+1)]

    if len(alpha) == 26:
        return 'true'
    else:
        return 'false'

# Driver program
if __name__ == "__main__":
    input = 'The quick brown fox jumps over the lazy dog'
    print (pangram(input))

Output

true

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