Matrix Transpose on RowMatrix in Spark

Question

Suppose I have a RowMatrix.

1. How can I transpose it. The API documentation does not seem to have a transpose method.
2. The Matrix has the transpose() me

Answer 1

Getting the transpose of RowMatrix in Java:

public static RowMatrix transposeRM(JavaSparkContext jsc, RowMatrix mat){
List newList=new ArrayList();
List vs = mat.rows().toJavaRDD().collect();
double [][] tmp=new double[(int)mat.numCols()][(int)mat.numRows()] ;

for(int i=0; i < vs.size(); i++){
    double[] rr=vs.get(i).toArray();
    for(int j=0; j < mat.numCols(); j++){
        tmp[j][i]=rr[j];
    }
}

for(int i=0; i < mat.numCols();i++)
    newList.add(Vectors.dense(tmp[i]));

JavaRDD rows2 = jsc.parallelize(newList);
RowMatrix newmat = new RowMatrix(rows2.rdd());
return (newmat);
}