code: public double[][] getFeaturesAsArray() {
  
          double[][] data = new double[this.size()][this.nrOfDimensions];
  
          int c = 0;
          for (DataObject d : dataList) {
              data[c] = d.getFeatures();
              c++;
          }
  
          return data;
      }
docs: Returns an array with all the features of all the objects in the set. Be aware that it does not copy the features
  so that any changes to the values of the features in this array will result in changes in
  the initial <code>DataObject</code>s.
  @return A <code>double[][]</code> with the features. The first dimension is the feature
  number, the second the values in the feature.
  @see DataObject