Re: creation of 2d matrix in colt library

From:
Robert <robert@gmail.inavild>
Newsgroups:
comp.lang.java.programmer
Date:
Thu, 21 Aug 2008 13:12:10 +0200
Message-ID:
<48ad4d0e$0$960$ba4acef3@news.orange.fr>
harryos a ?crit :

hi
i am using colt library(http://acs.lbl.gov/~hoschek/colt/) to do
matrix ops
i want to create a 2d matrix from a double[] .But the library provides
only DenseDoubleMatrix2D constructors that take in double[][].Is there
any way i can create a 2D matrix with this library?

Do i have to extend the class and add a constructor to take double[]?

i did something like

import cern.colt.matrix.impl.DenseDoubleMatrix2D;

class MyMatrix2D extends DenseDoubleMatrix2D{
  public MyMatrix2D(double[] vals ,int rows){
        super(rows,(rows != 0 ? vals.length/rows : 0));
        int columns=(rows != 0 ? vals.length/rows : 0);
        if (rows*columns != vals.length) {
             throw new IllegalArgumentException("Array length must be a
multiple of "+rows);
          }
        double[][]data = new double[rows][columns];
        for (int i = 0; i < rows; i++) {
        for (int j = 0; j < columns; j++) {
          data[i][j] = vals[i+j*rows];
           }
        }
        super.assign(data);
    }

  public MyMatrix2D(double[][] data){
        super(data);
    }

}

this works.and i can create MyMatrix2D objects from a double[] and an
'expected number of rows' value.but i am not sure if i am reinventing
the wheel..Any experts in colt library pls advise.
thanks


It seems, you find the shortest code. You could use a factory method,
sparring you to add your class.

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