Creating a 🐍📦 with tests

[dpshelio]

Help Charlene to test her package (#25) (remember to commit after each step, if appropriate).

1. Choose who in your team is writing now! (make sure you've pulled the latest changes from your team's fork.)

2. Create a tests directory inside sagittal_average so it looks like

   Desktop/ # if you cloned it there
   └── sagittal_average/
       ├── .git/
       ├── pyproject.toml
       ├── sagittal_average/
       └── tests/
   

3. Add a test to avoid the confusion between rows and columns

   TEST_DIR = Path(__file__).parent   
   
   def test_average():
       # Creates input file
       data_input = np.zeros((20, 20))
       data_input[-1, :] = 1
       # The expeted result is all zeros, except the last one, it should be 1
       expected = np.zeros(20)
       expected[-1] = 1
   
       np.savetxt(TEST_DIR / "brain_sample.csv", data_input, fmt='%d', delimiter=',')
   
       # run python program
       run_averages(file_input=TEST_DIR / "brain_sample.csv",
                    file_output=TEST_DIR / "brain_average.csv")
   
       # Check result
       result = np.loadtxt(TEST_DIR / "brain_average.csv",  delimiter=',')
       np.testing.assert_array_equal(result, expected)   

4. Fix sagittal_brain.py (the code wrongly averages over the columns, not the rows), make sure the test passes and commit these changes.

5. Try to install it by running pip install -e . where the pyproject.toml is, and then run the tests with pytest.

6. Share your solution as a pull request to Charlene's repository mentioning this issue (by including the text Addresses UCL-ARC-RSEworkshop-summer-25/RSE-Classwork#26 in the pull request description), remember to mention your team members too! (with @github_username)

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