Exercise - Working with Git

Each working group must implement the functions illustrated in the previous lessons regarding the loading of MNIST digit dataset and the computation of the centroids using Git tools for shared development.

The goal is to pass the automated tests in the project for the main branch and push to release.

If all the functions have been correctly implemented, you will find a passed green badge under GitHub Actions. If the tests are failing, a red failed badge will be displayed.

In particular each group must develop:

• load_mnist(csv_filename), load the MNIST dataset (available in data/mnist_data.csv)
• split_data(x, y, fract_tr=0.5), split data (return 2 sets, training and test)
• NMC.fit(x, y), compute the average centroid for each class for training set
• NMC.predict(x), predict the class of each sample

All functions must be added to the fun_utils.py and nmc.py files, which already contain the signature of the required functions.

Tests are available inside tests/test.py script.

By default the following libraries can be used:

• numpy
• scikit-learn
• matplotlib
• pandas

Change the requirements.txt file by adding the name of any new dependency if necessary.

Workflow details:

1. The team leader only should fork the current project and provide the repository url to other team members. The team leader must also add other team members to his project using the Settings -> Members menu of the GitHub project. Members should be added with Maintainer role. All team members can now clone the project locally.
2. Each group should discuss how to develop each function (example: if any extra function is needed, what it should return, ...).
3. Each group should then discuss which function each team member should implement.
4. Development of each function must be done in a specific branch, which must be pushed to the remote after creation. No direct commits into the main branch should be done
5. Each team member is suggested to commit local changes to remote as often as possible, so that other team members can see the progress on the code via the project page.
6. During the development, team members are encouraged to discuss code implementation and possible problems.
7. If needed, changes from other feature branches can be merged into a specific feature branch. Use any Git tool needed to correctly integrate the changes from multiple branches.
8. After the development of a specific feature has been completed, the relative branch should be merged into main.
9. The Activities should now be consulted to see the result of the automated tests. Depending on the load of the test runners, the pipeline could show the pending status for quite a while. Just wait until a runner picked the job. Recall that the test scripts can be also run locally.
10. If any change to the code is necessary, it should be developed in the branch relative to the specific feature and merged into master to see if tests are then passing.
11. When all tests are passing, the release branch should be created from the branch main. The tests will be run for the release branch too and must succeed.
12. When all tests are passing for the release branch, the last commit in that branch should be tagged as v1.0.

Details about functions and variables

Common variables:

• y: labels (one for each image) (numpy array)
• x: set of images. numpy array of size (nImages, nFeatures). Each row represents an image.

load_mnist(csv_filename):
    """Load the MNIST dataset.
    
    input:
        csv_filename: string with the path to the dataset to load
    
    output:    
        X: set of images (numpy array)
        y: labels (numpy array)

    """

split_data(x, y, fract_tr):
    """Split the data X,y into two random subsets.
    
    input:
        x: set of images
        y: labels
        fract_tr: float, percentage of samples to put in the training set.
            If necessary, number of samples in the training set is rounded to
            the lowest integer number.
    
    output:
        Xtr: set of images (numpy array, training set)
        Xts: set of images (numpy array, test set)
        ytr: labels (numpy array, training set)
        yts: labels (numpy array, test set)
    
    """


NMC.fit(x, y):
    """Compute the average centroid for each class.

    This function should populate the `._centroids` attribute
    with a numpy array of shape (num_classes, num_features).
    
    input:
        x: set of images (training set, numpy array)
        y: labels (training set, numpy array)
    
    """

NMC.predict(x):
    """Predict the class of each input.
    
    input:
        x: set of images (test set, numpy array)

    output:
        y: labels (numpy array)
    
    """