Convert numpy arrays of features and labels into
    an RDD of pairs.

    :param sc: Spark context
    :param features: numpy array with features
    :param labels: numpy array with labels
    :return: Spark RDD with feature-label pairs

def to_simple_rdd(sc, features, labels):
    """Convert numpy arrays of features and labels into
    an RDD of pairs.

    :param sc: Spark context
    :param features: numpy array with features
    :param labels: numpy array with labels
    :return: Spark RDD with feature-label pairs
    """
    pairs = [(x, y) for x, y in zip(features, labels)]
    return sc.parallelize(pairs)