Simple statistics using commons-math3

SimpleStatistics.java

  final DescriptiveStatistics descriptiveStats = new DescriptiveStatistics(); // stores values
  final SummaryStatistics summaryStats = new SummaryStatistics(); // doesn't store values
  final Frequency frequency = new Frequency();

  // add numbers into our stats
  for(int i=0; i < NUM_VALUES; ++i) {
      values[i] = rng.nextInt(MAX_VALUE);

      descriptiveStats.addValue(values[i]);
      summaryStats.addValue(values[i]);
      frequency.addValue(values[i]);
  }

  // print out some standard stats
  System.out.println("MIN: " + summaryStats.getMin());
  System.out.println("AVG: " + String.format("%.3f", summaryStats.getMean()));
  System.out.println("MAX: " + summaryStats.getMax());

  // get some more complex stats only offered by DescriptiveStatistics
  System.out.println("90%: " + descriptiveStats.getPercentile(90));
  System.out.println("MEDIAN: " + descriptiveStats.getPercentile(50));
  System.out.println("SKEWNESS: " + String.format("%.4f", descriptiveStats.getSkewness()));
  System.out.println("KURTOSIS: " + String.format("%.4f", descriptiveStats.getKurtosis()));

  // quick and dirty stats (need a little help from Guava to convert from int[] to double[])
  System.out.println("MIN: " + StatUtils.min(Doubles.toArray(Ints.asList(values))));
  System.out.println("AVG: " + String.format("%.4f", StatUtils.mean(Doubles.toArray(Ints.asList(values)))));
  System.out.println("MAX: " + StatUtils.max(Doubles.toArray(Ints.asList(values))));

  // some stats based upon frequencies
  System.out.println("NUM OF 7s: " + frequency.getCount(7));
  System.out.println("CUMULATIVE FREQUENCY OF 7: " + frequency.getCumFreq(7));
  System.out.println("PERCENTAGE OF 7s: " + frequency.getPct(7));