How to transpose an array using functions from libraries?

Question

How can I transpose an array using functions from libraries? I have downloaded and used the library Colt from here: http://acs.lbl.gov/software/colt/api/index.html. I tried :

DoubleMatrix1D array;
array = new DenseDoubleMatrix1D(4);
for (int i=0; i<4; i++)
    array.set(i,i);
DoubleMatrix1D transpose = array.viewDice();

but it doesn't work, as I get the error:

The method viewDice() is undefined for the type DoubleMatrix1D

Any ideas?

Answer 1

1D matrices don't contain any information about how they are oriented. So you would need to supply this information in order to transpose it. For example, if you are using a row vector, you have a 1xm matrix, so you would need an mx1 column vector to contain the transpose.

Try this:

DoubleMatrix2D transpose = new DenseDoubleMatrix2D(4,1);
for (int i=0; i<4; i++) {
    transpose.setQuick(i,0,array.getQuick(i));
}

If instead you have a column vector, the transpose would be a row vector:

DoubleMatrix2D transpose = new DenseDoubleMatrix2D(1,4);
for (int i=0; i<4; i++) {
    transpose.setQuick(0,i,array.getQuick(i));
}

Answer 2

This means that in the class DoubleMatrix1D the method viewDice() doesnt exists! So you barely can use it :).

According to documentation, you can use this :

 double[]   toArray() 
          Constructs and returns a 1-dimensional array containing the cell values.

Or maybe this :

 DoubleMatrix1D copy() 
          Constructs and returns a deep copy of the receiver.