Average absolute difference

gistfile1.java

/**
 * @return Vector [ (1 / n ) * ∑ |b - mean_b|, for b in {x,y,z} ]
 */
public static double[] computeAvgAbsDifference(JavaRDD<double[]> data, double[] mean) {

  // then for each point x compute x - mean
  // then apply an absolute value: |x - mean|
  JavaRDD<Vector> abs = data.map(record -> new double[]{Math.abs(record[0] - mean[0]),
                                                        Math.abs(record[1] - mean[1]),
                                                        Math.abs(record[2] - mean[2])})
                            .map(Vectors::dense);

  // And to finish apply the mean: for each axis (1 / n ) * ∑ |b - mean|
  return Statistics.colStats(abs.rdd()).mean().toArray();

}