def distance(features1, features2):
    """The Euclidean distance between two arrays of feature values."""
    distances = make_array()
    for i in range(len(features1)):
        dist = (float(features1.item(i)) - float(features2.item(i)))**2
        distances = np.append(distances, dist)
    return np.sqrt(sum(distances))

array1 = np.array(train_movies.row(0))
array2 = np.array(test_movies.row(0))
distance_first_to_first = distance(array1[6::], array2[6::])
distance_first_to_first