以下是带有两种边缘的neo4j图。首先，我们遍历边（BFS），然后标准化每种边的属性值。但是，当在不同的循环中检索值时，将打印错误的值。
这看起来非常奇怪。可能是我错过了什么。如果有的话，这将是非常有帮助的 一个让我纠正或建议我一个更好的方法来避免这个错误。在此先感谢：）
package org.neo4j.examples;
import java.io.File;
import java.util.HashMap;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Path;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.Transaction;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;
import org.neo4j.graphdb.traversal.Evaluator;
import org.neo4j.graphdb.traversal.Evaluators;
import org.neo4j.graphdb.traversal.TraversalDescription;
import org.neo4j.graphdb.traversal.Traverser;
import org.neo4j.graphdb.traversal.Uniqueness;
import org.neo4j.kernel.Traversal;
public class MyNeo4jExpt {
public enum RelTypes implements RelationshipType {
CO_OCCURANCE, CAMPAIGN
}
private static final String MY_TRAVERSAL_DB = "target/my-traversal-db";
private GraphDatabaseService graphDb;
static Node shop1 = null;
Node shop2 = null;
Node shop3 = null;
public static void main(String[] args) {
// TODO Auto-generated method stub
MyNeo4jExpt matrix = new MyNeo4jExpt();
matrix.setUp();
matrix.normalizeRelations(shop1);
matrix.shutdown();
}
public void setUp() {
deleteFileOrDirectory(new File(MY_TRAVERSAL_DB));
graphDb = new GraphDatabaseFactory()
.newEmbeddedDatabase(MY_TRAVERSAL_DB);
registerShutdownHook();
createNodespace();
}
public void shutdown() {
graphDb.shutdown();
}
public void createNodespace() {
try (Transaction tx = graphDb.beginTx()) {
// Create shop1
shop1 = graphDb.createNode();
shop1.setProperty("name", "FurnitureShop-1");
// create shop2
shop2 = graphDb.createNode();
shop2.setProperty("name", "FurnitureShop-2");
// create shop3
shop3 = graphDb.createNode();
shop3.setProperty("name", "FurnitureShop-3");
// ////// connect shop1 to shop2 ///////
Relationship rel = shop1.createRelationshipTo(shop2,
RelTypes.CO_OCCURANCE);
rel.setProperty("coOccurence", (Double) 5.0);
rel = shop1.createRelationshipTo(shop2, RelTypes.CAMPAIGN);
rel.setProperty("furniture", (Double) 0.6);
rel.setProperty("chair", (Double) 0.6);
rel.setProperty("table", (Double) 0.6);
// ///////////////////////////////////////
// ///// connect shop1 to shop3///////
rel = shop1.createRelationshipTo(shop3, RelTypes.CAMPAIGN);
rel.setProperty("furniture", (Double) 0.7);
rel.setProperty("sofa", (Double) 0.7);
// ////////////////////////////////////////
// ////// connect shop3 to shop2 ///////
rel = shop3.createRelationshipTo(shop2, RelTypes.CO_OCCURANCE);
rel.setProperty("coOccurence", (Double) 4.0);
// ///////////////////////////////////////
tx.success();
}
}
// this function calls a BFS on the given node
// and normalize relation properties w.r.t. the
// right edge type (RelType)
private Traverser normalizeRelations(final Node node) {
Traverser friendsTraverser = null;
HashMap<Relationship, Path> relHash = new HashMap<Relationship, Path>();
try (Transaction tx = graphDb.beginTx()) {
if (node == null) {
System.out.println("\nNULL NODE\n");
return null;
}
friendsTraverser = getFriends(node);
if (friendsTraverser == null) {
System.err.println("NULL TRAVERSER");
return null;
}
HashMap<RelationshipType, Double> maxVal = new HashMap<RelationshipType, Double>();
String temp = "";
try (Transaction tx2 = graphDb.beginTx()) {
for (Path friendPath : friendsTraverser) {
System.out.println("\nAt depth " + friendPath.length()
+ " => " + friendPath.toString());
// output += friendPath.startNode().getProperty("name")+ " "
// ;
for (Relationship rel : friendPath.relationships()) {
temp = " " + rel.getStartNode().getProperty("name");
for (String name : rel.getPropertyKeys()) {
Double propVal = (Double) rel.getProperty(name);
temp += "---" + "(" + name + ", " + propVal + ")";
if ((maxVal.get(rel.getType()) == null)
|| (propVal > maxVal.get(rel.getType()))) {
maxVal.put(rel.getType(), propVal); // <----
// Save the
// Max Value
// for
// Particular
// Rel Type
}
}
temp += "----" + rel.getEndNode().getProperty("name")
+ "\n";
}
// numberOfFriends++;
System.out.println(temp);
}
tx2.success();
}
System.out.println("*************************************");
System.out.println("**** Devide w.r.t maxVal = "
+ maxVal.entrySet()
+ "And Normalized Values Are:*************");
System.out.println("*************************************");
temp = "";
for (Path friendPath : friendsTraverser) {
System.out.println("\nAt depth " + friendPath.length() + " => "
+ friendPath.toString());
for (Relationship rel : friendPath.relationships()) {
temp = "" + rel.getStartNode().getProperty("name");
try (Transaction tx3 = graphDb.beginTx()) {
for (String propName : rel.getPropertyKeys()) {
Double propVal = (Double) rel.getProperty(propName)
/ maxVal.get(rel.getType());
rel.setProperty(propName, propVal);
temp += "---" + "(" + propName + ", "
+ rel.getProperty(propName) + ")";
}
tx3.success();
}
temp += "----" + rel.getEndNode().getProperty("name")
+ "\n";
}
System.out.println(temp);
}
tx.success();
}
System.out
.println("\n+++++++++++++NOW WRONG VALUES WILL BE PRINTED+++++++++++++++");
try (Transaction tx = graphDb.beginTx()) {
String temp = "";
for (Path friendPath : friendsTraverser) {
System.out.println("\nAt depth " + friendPath.length() + " => "
+ friendPath.toString());
for (Relationship rel : friendPath.relationships()) {
temp = " " + rel.getStartNode().getProperty("name");
for (String propName : rel.getPropertyKeys()) {
temp += "---" + "(" + propName + ", "
+ rel.getProperty(propName) + ")";
}
temp += "----" + rel.getEndNode().getProperty("name")
+ "\n";
}
System.out.println(temp);
}
tx.success();
}
return friendsTraverser;
}
// START SNIPPET: get-friends
private static Traverser getFriends(final Node person) {
TraversalDescription td = Traversal.description().breadthFirst()
.relationships(RelTypes.CAMPAIGN, Direction.BOTH)
.relationships(RelTypes.CO_OCCURANCE, Direction.BOTH)
.evaluator(Evaluators.toDepth(10))
.evaluator(Evaluators.excludeStartPosition())
.uniqueness(Uniqueness.RELATIONSHIP_GLOBAL);
return td.traverse(person);
}
// END SNIPPET: get-friends
private void registerShutdownHook() {
// Registers a shutdown hook for the Neo4j instance so that it
// shuts down nicely when the VM exits (even if you "Ctrl-C" the
// running example before it's completed)
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
graphDb.shutdown();
}
});
}
private static void deleteFileOrDirectory(final File file) {
if (!file.exists()) {
return;
}
if (file.isDirectory()) {
for (File child : file.listFiles()) {
deleteFileOrDirectory(child);
}
} else {
file.delete();
}
}
}
At depth 1 => (0)--[CAMPAIGN,1]-->(1)
FurnitureShop-1---(furniture, 0.6)---(chair, 0.6)---(table, 0.6)----FurnitureShop-2
At depth 1 => (0)--[CAMPAIGN,2]-->(2)
FurnitureShop-1---(furniture, 0.7)---(sofa, 0.7)----FurnitureShop-3
At depth 1 => (0)--[CO_OCCURANCE,0]-->(1)
FurnitureShop-1---(coOccurence, 5.0)----FurnitureShop-2
At depth 2 => (0)--[CAMPAIGN,1]-->(1)<--[CO_OCCURANCE,3]--(2)
FurnitureShop-3---(coOccurence, 4.0)----FurnitureShop-2
*************************************
**** Devide w.r.t maxVal = [RelationshipTypeToken[name:CO_OCCURANCE, id:0]=5.0, RelationshipTypeToken[name:CAMPAIGN, id:1]=0.7]And Normalized Values Are:*************
*************************************
At depth 1 => (0)--[CAMPAIGN,1]-->(1)
FurnitureShop-1---**(furniture, 0.8571428571428572)---(chair, 0.8571428571428572)---(table, 0.8571428571428572)**----FurnitureShop-2
At depth 1 => (0)--[CAMPAIGN,2]-->(2)
FurnitureShop-1---(furniture, 1.0)---(sofa, 1.0)----FurnitureShop-3
At depth 1 => (0)--[CO_OCCURANCE,0]-->(1)
FurnitureShop-1---(coOccurence, 1.0)----FurnitureShop-2
At depth 2 => (0)--[CAMPAIGN,1]-->(1)<--[CO_OCCURANCE,3]--(2)
FurnitureShop-3---(coOccurence, 0.8)----FurnitureShop-2
+++++++++++++NOW **WRONG VALUES** WILL BE PRINTED+++++++++++++++
At depth 1 => (0)--[CAMPAIGN,1]-->(1)
FurnitureShop-1---**(furniture, 1.2244897959183676)---(chair, 1.2244897959183676)**---(table, 1.2244897959183676)----FurnitureShop-2
At depth 1 => (0)--[CAMPAIGN,2]-->(2)
FurnitureShop-1---(furniture, 1.0)---(sofa, 1.0)----FurnitureShop-3
At depth 1 => (0)--[CO_OCCURANCE,0]-->(1)
FurnitureShop-1---(coOccurence, 1.0)----FurnitureShop-2
At depth 2 => (0)--[CAMPAIGN,1]-->(1)<--[CO_OCCURANCE,3]--(2)
FurnitureShop-3---(coOccurence, 0.8)----FurnitureShop-2
答案 0 :(得分：1)