package com.jgaap.eventCullers;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import com.jgaap.backend.Utils;
import com.jgaap.generics.EventCullingException;
import com.jgaap.generics.FilterEventCuller;
import com.jgaap.util.Event;
import com.jgaap.util.EventHistogram;
import com.jgaap.util.EventSet;
import com.jgaap.util.Pair;
/**
*Analyze N events with the highest index of dispersion
*D = stdev^2/mean
*
* @author Christine Gray
*/
public class IndexOfDispersion extends FilterEventCuller {
public IndexOfDispersion() {
super();
addParams("numEvents", "N", "50", new String[] { "1", "2", "3", "4",
"5", "6", "7", "8", "9", "10", "15", "20", "25", "30", "40",
"45", "50", "75", "100", "150", "200" }, true);
addParams("Informative", "I", "Most", new String[] { "Most","Least"}, false);
}
@Override
public Set<Event> train(List<EventSet> eventSets)
throws EventCullingException {
int numEvents = getParameter("numEvents", 50);
String informative = getParameter("Informative", "Most");
EventHistogram hist = new EventHistogram();
for (EventSet oneSet : eventSets) {
for (Event e : oneSet) {
hist.add(e);
}
}
List<Pair<Event,Double>> IoD = new ArrayList<Pair<Event,Double>>();
List<EventHistogram> eventHistograms = new ArrayList<EventHistogram>(eventSets.size());
for (EventSet eventSet : eventSets) {
eventHistograms.add(new EventHistogram(eventSet));
}
for (Event event : hist) {
double mean;
double stddev;
List<Double>frequencies = new ArrayList<Double>();
/*
* Add all the frequencies of each event to a list
* Then take the standard deviation of the list
*/
for (EventHistogram eventHistogram : eventHistograms) {
frequencies.add((double) eventHistogram.getAbsoluteFrequency(event));
}
stddev = Utils.stddev(frequencies);
mean = mean(frequencies,0.0,0.0);
/*
* Add Standard deviation^2 / mean to the list of Index of Dispersion
*/
IoD.add(new Pair<Event,Double>(event, Math.pow(stddev,2)/mean,2));
}
Collections.sort(IoD);
if(informative.equals("Most")){
Collections.reverse(IoD);
}
int counter = 0;
Set<Event> events = new HashSet<Event>(numEvents);
for(Pair<Event, Double> event : IoD){
counter++;
events.add(event.getFirst());
if(counter == numEvents)
break;
}
return events;
}
@Override
public String displayName() {
return "Index of Dispersion";
}
@Override
public String tooltipText() {
return "Analyze N events with the highest index of dispersion";
}
@Override
public boolean showInGUI() {
return true;
}
@Override
public String longDescription(){
return "Analyze N events with the highest index of dispersion\n"
+"D = \u03C3\u00B2/\u03BC";
}
/*
* Recursively find the mean of a list of frequencies
*/
double mean(List<Double>frequencies, double count, double mean){
if(frequencies.isEmpty()){
return mean/count;
}
mean+=frequencies.remove(0);
count++;
return mean(frequencies,count, mean);
}
}