/** Stable median calculation. */
public double calcStableMedian(double lowerFrac, double upperFrac, IntArrayList list) {
// This works for any size!
list.trimToSize();
Arrays.sort(list.elements());
int sum = 0;
int cnt = 0;
for (int i = (int) (lowerFrac * list.size()); i < (int) (list.size() * upperFrac); i++) {
sum += list.get(i);
cnt++;
}
return (double) sum / cnt;
// below is the original. it Relies on bucket-sorting. It should be perfectly possible to write
// a linear-time stable median
// based on the normal linear-time median algorithm. This is needed to handle non-8bit images.
// Value might be off a bit but not much (need to think of indexing), and it doesn't matter for
// this application
/*
int numbins=66000;
int[] elem=list.elements();
int numElem=list.size();
//Calculate histogram
int[] histogram=new int[numbins];
//int[] elem=curBgOutside.elements();
//int numElem=curBgOutside.size();
for(int i=0;i<numElem;i++)
histogram[elem[i]]++;
int jumpElem=0;
int lowerIndex=(int)(numElem*lowerFrac);
int upperIndex=(int)(numElem*upperFrac);
int sum=0;
int cnt=0;
for(int i=0;i<numbins;i++)
{
int thisNum=histogram[i];
int take=Math.min(upperIndex,jumpElem+thisNum)-Math.max(lowerIndex, jumpElem);
if(take>0)
{
sum+=take*i;
cnt+=take;
}
jumpElem+=thisNum;
}
return (double)sum/cnt;
*/
}
