Scrub with a list comprehension

Isogram
Isogram in Python
def is_isogram(phrase):
    scrubbed = [ltr.lower() for ltr in phrase if ltr.isalpha()]
    return len(set(scrubbed)) == len(scrubbed)

For this approach, a list comprehension is used to iterate the letters in the input phrase string.

  • In the code example, ltr is the name given to each letter iterated in the for loop.
  • The result of each iteration is ltr.lower(), which is the lowercased letter being iterated. All of the letters are lowercased so that letters of different cases will become the same letter for comparison purposes, since A and a are considered to be the same letter.
  • The iterable part of the list comprehension is the input phrase.
  • The letters are filtered by the use of the optional conditional logic: if ltr.isalpha(). isalpha() returns True if the letter being iterated is alphabetic.

When the list comprehension is done, the scrubbed variable will be a list holding only lowercased alphabetic characters.

  • A set is constructed from the scrubbed list and its len is compared with the len of the the scrubbed list. Since a set holds only unique values, the phrase will be an isogram if its number of unique letters is the same as its total number of letters. The function returns whether the number of unique letters equals the total number of letters.
  • For Alpha it would return False, because a is considered to repeat A, so the number of unique letters in Alpha is 4, and the total number of letters in Alpha is 5.
  • For Bravo it would return True, since the number of unique letters in Bravo is 5, and the total number of letters in Bravo is 5.
6th Nov 2024 · Found it useful?