我有这张图：
A-> B，A-> C，B-> C，C-> D，A-> E
我想在Java中找到“ A”和“ D”之间的最短路径。我用了：
s= select from ( select expand( shortestPath("+ first_vertex.getId() +", "+ second_vertex.getId() +").outE()))
for (Edge edge : (Iterable<Edge>) g.command(
new OCommandSQL(s)).execute()) {
System.out.println(edge);
}
我得到的问题不是预期的结果：
A - B
A - C
A - E
C - D
当我关注顶点而不是边缘时，我得到了正确的短路径：
A-> C-> D
为什么边缘无法像我那样工作？
编辑：
Updated graph
当我在附件图像中具有该图时，并且我想使用您的方法找到“ A”和“ D”之间的最短路径时，我仍然没有边缘：最短路径（顶点）：ACD最短路径（边缘）：最短路径（顶点）不应该是：A，F，E，D吗？如果现在我想找到“ D”和“ A”之间的最短路径，那么更新后也不会收到任何提示。
最佳答案
我创建了一个新答案，因为代码与上一个完全不同。
使用此代码，您只需设置StartNode（Vstart）和endNode（Vend），然后返回ShortestPath（指边），并始终将方向为“ out”（与第一个节点相比）和方向为“ in”（如果有），与第一个节点。
该操作基于提取从Orient的工作ShortestPath（）返回的顶点，因为这些顶点中的每一个都控制着边。
public class PathEdge {
static final String REMOTE = "remote:localhost/";
static final String NOMEDB = "ShortestPath2";
static final String CURRENTPATH = REMOTE + NOMEDB;
public static void main(String[] args) throws IOException {
OServerAdmin serverAdmin = new OServerAdmin(CURRENTPATH).connect("root", "root");
OrientGraphNoTx g = new OrientGraphFactory(CURRENTPATH).getNoTx();
String Vstart = "a"; //----- to set
String Vend = "d"; // ---- to set
String queryClassName = "Nodo"; //----- to set
String queryProperty = "name"; //----- to set
String edgeNAme = "is_a"; //----- to set
String direction = "'OUT'"; //----- to set "BOTH" (incoming and outgoing), "OUT" (outgoing) and "IN" (incoming)
String query1 = "select from "+queryClassName+" where "+queryProperty+" = '"+Vstart+"'";
Iterable<Vertex> start = g.command(new OSQLSynchQuery<Vertex>(query1)).execute();
String query2 = "select from "+queryClassName+" where "+queryProperty+" = '"+Vend+"'";
Iterable<Vertex> end = g.command(new OSQLSynchQuery<Vertex>(query2)).execute();
long startTime = System.currentTimeMillis();
showPath(g, start.iterator().next().getId().toString(), end.iterator().next().getId().toString(), edgeNAme, direction);
long estimatedTime = System.currentTimeMillis() - startTime;
System.out.println("");
System.out.println("TIME EXECUTE: "+estimatedTime+"ms");
}
public static void showPath (OrientGraphNoTx g, String Vstart, String Vend , String edge, String direction) {
String s = "";
int position = 0;
int maxsize = 0;
s= "select expand(shortestPath(" + Vstart + ", " + Vend+", "+direction+"))";
Iterable<Vertex> result = g.command(new OSQLSynchQuery<Vertex>(s)).execute();
List<OrientVertex> listaVertex = new ArrayList<OrientVertex>();
CollectionUtils.addAll(listaVertex, result.iterator());
List<String> listPRECout = new ArrayList<String>();
List<String> listPRECin = new ArrayList<String>();
List<String> listFOLLout = new ArrayList<String>();
List<String> listFOLLin = new ArrayList<String>();
List<String> resultOut = new ArrayList<String>();
List<String> resultIn = new ArrayList<String>();
//per ogni vertice recupera archi uscenti ed entranti
Iterable<Edge> tempOut;
Iterable<Edge> tempIn;
String singleIn = "";
String singleOut = "";
boolean finded = false;
System.out.println("SHORTEST PATH (vertex [direction "+direction+"]):");
for (int v=0; v<listaVertex.size(); v++) {
System.out.print(listaVertex.get(v).getProperty("name")+ " " );
}
System.out.println("");
System.out.println("");
maxsize = listaVertex.size()-1;
for (int v=0; v<maxsize; v++) {
//--------FIRST VERTEX OF THE SHORTEST PATH
tempOut = listaVertex.get(v).getEdges(Direction.OUT, edge);
tempIn = listaVertex.get(v).getEdges(Direction.IN, edge);
//set listPRECin
for(Edge edgeIn : tempIn) {
listPRECin.add(edgeIn.getId().toString()); //position x = rid
listPRECin.add(edgeIn.getLabel()); //position x+1 = label
}
//set listPRECout
for(Edge edgeOut : tempOut) {
listPRECout.add(edgeOut.getId().toString()); //position x = rid
listPRECout.add(edgeOut.getLabel()); //position x+1 = label
}
//--------SECOND VERTEX OF THE SHORTEST PATH
tempOut = listaVertex.get(v+1).getEdges(Direction.OUT, edge);
tempIn = listaVertex.get(v+1).getEdges(Direction.IN, edge);
//set listFOLLin
for(Edge edgeIn : tempIn) {
listFOLLin.add(edgeIn.getId().toString()); //position x = rid
listFOLLin.add(edgeIn.getLabel()); //position x+1 = label
}
//set listFOLLout
for(Edge edgeOut : tempOut) {
listFOLLout.add(edgeOut.getId().toString()); //position x = rid
listFOLLout.add(edgeOut.getLabel()); //position x+1 = label
}
//------MATCH LOGIC
//...compare PRECin with FOLLout
finded = false;
for(int i = 0; i<listPRECin.size(); i=i+2) {
singleIn = listPRECin.get(i);
for(int o = 0; o<listFOLLout.size(); o=o+2){
singleOut = listFOLLout.get(o);
if(singleIn.equals(singleOut)) {
//check is there a hole
if(v==0) {
resultIn.add(singleIn); //rid
resultIn.add(listPRECin.get(i+1)); //label
finded = true;
break;
} else if((v*2) == resultIn.size()) {
resultIn.add(singleIn); //rid
resultIn.add(listPRECin.get(i+1)); //label
finded = true;
break;
}
}
}
if(finded)break;
}
finded = false;
//...compare PRECout with FOLLin
for(int i = 0; i<listPRECout.size(); i=i+2) {
singleOut = listPRECout.get(i);
for(int o = 0; o<listFOLLin.size(); o=o+2){
singleIn = listFOLLin.get(o);
if(singleOut.equals(singleIn)) {
//check is there a hole
if(v==0) {
resultOut.add(singleOut); //rid
resultOut.add(listPRECout.get(i+1)); //label
finded = true;
break;
} else if((v*2) == resultOut.size()) {
resultOut.add(singleOut); //rid
resultOut.add(listPRECout.get(i+1)); //label
finded = true;
break;
}
}
}
if(finded)break;
}
//to empty out list
listPRECin.clear();
listPRECout.clear();
listFOLLin.clear();
listFOLLout.clear();
//cheack if it's in the penultimate vertex
position = v+1;
if( position==maxsize) {
break;
}
}
System.out.println("SHORTEST PATH (edge, out direction):");
if(resultOut.size()>0) {
for (int ind=0; ind<resultOut.size(); ind=ind+2) { //ind+2 so i get id[position x] and label [position x+1]
System.out.println("id:"+resultOut.get(ind)+", Label:"+resultOut.get(ind+1));
}
} else {
System.out.println("No edge in this direction (OUT)");
}
System.out.println("");
System.out.println("SHORTEST PATH (edge, in direction):");
if(resultIn.size()>0) {
for (int ind=0; ind<resultIn.size(); ind=ind+2) { //ind+2 so i get id[position x] and label [position x+1]
System.out.println("id:"+resultIn.get(ind)+", Label:"+resultIn.get(ind+1));
}
}else {
System.out.println("No edge in this direction (IN)");
}
}
}
编辑2
在ShortestPath函数中使用“方向”。
关于java - 如何在Orientdb中查找短路径(边而不是顶点)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/35885400/