code: public static RegressionDataSet getSampledDataSet(RegressionDataSet dataSet, int[] sampledCounts)
      {
          RegressionDataSet destination = new RegressionDataSet(dataSet.getNumNumericalVars(), dataSet.getCategories());
          for (int i = 0; i < sampledCounts.length; i++)
              for (int j = 0; j < sampledCounts[i]; j++)
              {
                  DataPoint dp = dataSet.getDataPoint(i);
                  destination.addDataPoint(dp, dataSet.getTargetValue(i));
              }
          return destination;
      }
docs: Creates a new data set from the given sample counts. Points sampled
  multiple times will have multiple entries in the data set.
  @param dataSet the data set that was sampled from
  @param sampledCounts the sampling values obtained from
  {@link #sampleWithReplacement(int[], int, java.util.Random) }
  @return a new sampled classification data set