source: tags/MetisMQIDemo/src/main/java/weka/clusterers/forMetisMQI/util/ContractedVertexTransformer.java

package weka.clusterers.forMetisMQI.util;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

import org.apache.commons.collections15.Transformer;

import weka.clusterers.forMetisMQI.graph.Node;

public class ContractedVertexTransformer implements Transformer<Node, String> {
        Map<Node,Set<Node>> mapContracted = null;

        public ContractedVertexTransformer(CoarserGraphElement cge) {
                mapContracted = new HashMap<Node,Set<Node>>();
                Iterator<Entry<Node,Node>> entryIterator = cge.getMap().entrySet().iterator();
                while(entryIterator.hasNext()) {
                        Entry<Node, Node> entry = entryIterator.next();
                        Node prevNode = entry.getKey();
                        Node mappedNode = entry.getValue();
                        if(!mapContracted.containsKey(mappedNode))
                                mapContracted.put(mappedNode, new HashSet<Node>());
                        mapContracted.get(mappedNode).add(prevNode);
                }
        }
        
        public String transform(Node n) {
                StringBuffer buffer = new StringBuffer();
                Iterator<Node> contracted = mapContracted.get(n).iterator();
                buffer.append("[");
                while(contracted.hasNext()) {
                        buffer.append(contracted.next().getId() + ", ");
                }
                if(buffer.length() > 1)
                        buffer.setLength(buffer.length() - 2);
                buffer.append("]");
                return buffer.toString();
        }

}