def generate_streak_matrix(weeks_data):
    """
    Create the streak matrix
        1 if the user committed
        0 if the user hasn't committed
        -1 to store null values

    :param weeks_data: week-wise contribution data of the user
    :return: matrix containing the values of the contribution streak
    """
    rows, columns = 7, len(weeks_data)
    streak_matrix = [[-1 for i in range(columns)] for y in range(rows)]

    i = 0
    for week in weeks_data:
        days = week['contributionDays']
        for day in days:
            if day['contributionCount'] > 0:
                streak_matrix[day['weekday']][i] = 1
            elif day['contributionCount'] == 0:
                streak_matrix[day['weekday']][i] = 0
        i += 1

    return streak_matrix