in Spark, there is a RowMatrix.columnSimilarities() method (see http://spark.apache.org/docs/latest/api/java/org/apache/spark/mllib/linalg/distributed/RowMatrix.html#columnSimilarities()) that returns An n x n sparse upper-triangular matrix of cosine similarities between columns of this matrix.How should I read it? If I try to implement an example from https://stackoverflow.com/a/1750187 as following: JavaRDD<Vector> rows = sc.parallelize(Arrays.asList(    new DenseVector(new double[]{2, 1, 0, 2, 0, 1, 1, 1}),    new DenseVector(new double[]{2, 1, 1, 1, 1, 0, 1, 1})));RowMatrix mat = new RowMatrix(rows.rdd());  List<Vector> sims = mat.columnSimilarities().toRowMatrix().rows().toJavaRDD().collect();for(Vector v: sims) {    System.out.println(v);}I get this(8,[6,7],[0.7071067811865475,0.7071067811865475])(8,[1,2,3,4,5,6,7],[0.9999999999999998,0.7071067811865475,0.9486832980505137,0.7071067811865475,0.7071067811865475,0.9999999999999998,0.9999999999999998])(8,[2,3,4,5,6,7],[0.7071067811865475,0.9486832980505137,0.7071067811865475,0.7071067811865475,0.9999999999999998,0.9999999999999998])(8,[7],[0.9999999999999998])(8,[4,5,6,7],[0.4472135954999579,0.8944271909999159,0.9486832980505137,0.9486832980505137])(8,[6,7],[0.7071067811865475,0.7071067811865475])(8,[3,4,6,7],[0.4472135954999579,1.0,0.7071067811865475,0.7071067811865475])How should I interpret it? How do I get the cosine angle 0.822 from this, as mentioned in the referenced stackoverflow post?Thanks!
How to interpret upper-triangular matrix of cosine similarities
apache spark;similarity