Determine if a word or phrase is an isogram.
An isogram (also known as a "nonpattern word") is a word or phrase without a repeating letter, however spaces and hyphens are allowed to appear multiple times.
Examples of isograms:
The word isograms, however, is not an isogram, because the s repeats.
Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include a message.
To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
raise Exception, you should write:
raise Exception("Meaningful message indicating the source of the error")
To run the tests, run the appropriate command below (why they are different):
Alternatively, you can tell Python to run the pytest module (allowing the same command to be used regardless of Python version):
python -m pytest isogram_test.py
-v: enable verbose output
-x: stop running tests on first failure
--ff: run failures from previous test before running other test cases
For other options, see
python -m pytest -h
Note that, when trying to submit an exercise, make sure the solution is in the
You can find your Exercism workspace by running
exercism debug and looking for the line that starts with
For more detailed information about running tests, code style and linting, please see the help page.
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
import unittest from isogram import is_isogram # Tests adapted from `problem-specifications//canonical-data.json` @ v1.2.0 class IsogramTest(unittest.TestCase): def test_empty_string(self): self.assertIs(is_isogram(""), True) def test_isogram_with_only_lower_case_characters(self): self.assertIs(is_isogram("isogram"), True) def test_word_with_one_duplicated_character(self): self.assertIs(is_isogram("eleven"), False) def test_longest_reported_english_isogram(self): self.assertIs(is_isogram("subdermatoglyphic"), True) def test_word_with_duplicated_character_in_mixed_case(self): self.assertIs(is_isogram("Alphabet"), False) def test_hypothetical_isogrammic_word_with_hyphen(self): self.assertIs(is_isogram("thumbscrew-japingly"), True) def test_isogram_with_duplicated_hyphen(self): self.assertIs(is_isogram("six-year-old"), True) def test_made_up_name_that_is_an_isogram(self): self.assertIs(is_isogram("Emily Jung Schwartzkopf"), True) def test_duplicated_character_in_the_middle(self): self.assertIs(is_isogram("accentor"), False) # Additional tests for this track def test_isogram_with_duplicated_letter_and_nonletter_character(self): self.assertIs(is_isogram("Aleph Bot Chap"), False) if __name__ == '__main__': unittest.main()
def is_isogram(str): """Return True if str is an isogram.""" clean_str = [ch.lower() for ch in str if ch.isalpha()] seen = set() for ch in clean_str: if ch in seen: return False seen.add(ch) return True
A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.
Here are some questions to help you reflect on this solution and learn the most from it.