public static TDoubleDoubleHashMap createCumulativeHistogram(TDoubleDoubleHashMap histogram){
  double[] keys=histogram.keys();
  Arrays.sort(keys);
  double sum=0;
  for (  double key : keys) {
    double val=histogram.get(key);
    sum+=val;
    histogram.put(key,sum);
  }
  return histogram;
}

public static TDoubleDoubleHashMap createCumulativeHistogram ( TDoubleDoubleHashMap histogram ) { double [ ] keys = histogram . keys ( ) ; Arrays . sort ( keys ) ; double sum = 0 ; for ( double key : keys ) { double val = histogram . get ( key ) ; sum += val ; histogram . put ( key , sum ) ; } return histogram ; }
creates a cumulative histogram where each bin height is the sum of the previous bin ' s height and the current bin ' s height .
