def get_label_map(file_path):
    """
    Build a dictionary for looking up training labels.

    Parameters
    ----------
    file_path : str

    Returns
    -------
    label_map : dict[str, str]
        The key is the class number (as an int).
    """
    label_map = {}
    with open(file_path) as fi:
        fi.readline()  # ignore header
        for line in fi:
            arr = line.split(',')
            label_map[int(arr[0])] = line
    return label_map