Check if two words are anagram

anagram.py

"""Classic interview question to check if two words are anagram."""
import collections
import itertools

import pytest

def is_anagram(first: str, second: str) -> bool:
  """Implementation of anagram checker with 3 different methods.

  Note:
    Method 1 - Uses brute force.
    Method 2 - Uses the built in `sorted` function.
    Method 3 - Uses `itertools`' Counter method.

    Method 3 is the fasted while Method 1 is the slowest at O(n!*n!)

  Args:
    first (str) - First word.
    second (str) - Second word.

  Return:
    (bool) - Whether `first` and `second` are anagrams.
  """
  # Method 1 (Brute force):
  # for permutation1 in itertools.permutation(first):
  #   for permutation2 in itertools.permutation(second):
  #     if permutation1 == permutation2:
  #       return True
  #  return False

  # Method 2 (Sort):
  # return sorted(first) == sorted(second)

  # Method 3 (Counter):
  return collections.Counter(first) == collections.Counter(second)

@pytest.mark.parametrize(
  ('first', 'second')
  (
    ('', ''),        # An emtpy string is a valid anagram.
    ('a', 'a'),      # Same 1 char string is a valid anagram.
    ('of', 'fo'),    # Same counts of same char is a valid anagram.
    ('oof', 'foo'),  # Same counts of same char is a valid anagram.
  )
)
def test_matches(first, second):
  """Test to show the first and second word is a valid anagram."""
  assert is_anagram(first, second) is True

@pytest.mark.parametrize(
  ('first', 'second'),
  (
    ('a', 'b'),      # Different 1 char isn't a valid anagram.
    ('of', 'off'),   # Different sized string isn't a valid anagram.
    ('oof', 'ffo'),  # Different counts of same char isn't an anagram.
  )
)
def test_not_matches(first, second):
  """Test to show the first and second word isn't a valid anagram."""
  assert is_anagram(first, second) is False

Classic interview question to check if two words are anagram.

Install PyTest to run tests:

$ virtualenv venv
created virtual environment CPython3.8.7.final.0-64 in 158ms
  creator CPython3Posix(dest=/Users/johndoe/workspace/venv, clear=False, no_vcs_ignore=False, global=False)
  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/Users/johndoe/Library/Application Support/virtualenv)
    added seed packages: pip==21.0.1, setuptools==53.0.0, wheel==0.36.2
  activators BashActivator,CShellActivator,FishActivator,PowerShellActivator,PythonActivator,XonshActivator
(venv) $ . venv/bin/activate
(venv) $ pip install pytest
Collecting pytest
  Using cached pytest-6.2.2-py3-none-any.whl (280 kB)
Collecting attrs>=19.2.0
  Using cached attrs-20.3.0-py2.py3-none-any.whl (49 kB)
Collecting packaging
  Using cached packaging-20.9-py2.py3-none-any.whl (40 kB)
Collecting toml
  Using cached toml-0.10.2-py2.py3-none-any.whl (16 kB)
Collecting pluggy<1.0.0a1,>=0.12
  Using cached pluggy-0.13.1-py2.py3-none-any.whl (18 kB)
Collecting iniconfig
  Using cached iniconfig-1.1.1-py2.py3-none-any.whl (5.0 kB)
Collecting py>=1.8.2
  Using cached py-1.10.0-py2.py3-none-any.whl (97 kB)
Collecting pyparsing>=2.0.2
  Using cached pyparsing-2.4.7-py2.py3-none-any.whl (67 kB)
Installing collected packages: pyparsing, toml, py, pluggy, packaging, iniconfig, attrs, pytest
Successfully installed attrs-20.3.0 iniconfig-1.1.1 packaging-20.9 pluggy-0.13.1 py-1.10.0 pyparsing-2.4.7 pytest-6.2.2 toml-0.10.2

You can run the test like so:

$ pytest anagram.py
================================================= test session starts ==================================================
platform darwin -- Python 3.8.7, pytest-6.2.2, py-1.10.0, pluggy-0.13.1
rootdir: /Users/johndoe/workspace
collected 7 items                                                                                                      
anagram.py .......                                                                                               [100%]
================================================== 7 passed in 0.01s ===================================================