package com.metamx.collections.spatial.split;
import com.metamx.collections.spatial.Node;
import com.metamx.collections.spatial.RTreeUtils;
import com.metamx.collections.bitmap.BitmapFactory;
import java.util.List;
/**
*/
public class QuadraticGutmanSplitStrategy extends GutmanSplitStrategy
{
public QuadraticGutmanSplitStrategy(int minNumChildren, int maxNumChildren, BitmapFactory bf)
{
super(minNumChildren, maxNumChildren, bf);
}
@Override
public Node[] pickSeeds(List<Node> nodes)
{
double highestCost = Double.MIN_VALUE;
int[] highestCostIndices = new int[2];
for (int i = 0; i < nodes.size() - 1; i++) {
for (int j = i + 1; j < nodes.size(); j++) {
double cost = RTreeUtils.getEnclosingArea(nodes.get(i), nodes.get(j)) -
nodes.get(i).getArea() - nodes.get(j).getArea();
if (cost > highestCost) {
highestCost = cost;
highestCostIndices[0] = i;
highestCostIndices[1] = j;
}
}
}
return new Node[]{nodes.remove(highestCostIndices[0]), nodes.remove(highestCostIndices[1] - 1)};
}
@Override
public Node pickNext(List<Node> nodes, Node[] groups)
{
double highestCost = Double.MIN_VALUE;
Node costlyNode = null;
int counter = 0;
int index = -1;
for (Node node : nodes) {
double group0Cost = RTreeUtils.getEnclosingArea(node, groups[0]);
double group1Cost = RTreeUtils.getEnclosingArea(node, groups[1]);
double cost = Math.abs(group0Cost - group1Cost);
if (cost > highestCost) {
highestCost = cost;
costlyNode = node;
index = counter;
}
counter++;
}
if (costlyNode != null) {
nodes.remove(index);
}
return costlyNode;
}
}