Tinkerpop/Gremlin合并顶点(和边) [英] Tinkerpop/gremlin merge vertices (and edges)

问题描述

是否有一种简单的方法来替换或合并顶点并保持/合并现有边?还是只是手动从顶点复制所有属性，并重新创建现有的边线和所有(元)属性，然后删除多余的顶点?

Is there an easy way to replace or merge vertices and keep/merge existing edges? Or just manually copy all properties from the vertex and recreate existing edges and all (meta-)properties and then drop the superfluous vertex?

推荐答案

好的，如上面的评论所述，您将在OLTP中进行匹配.这意味着您可能会有一个具体的切入点.让我们组成一个简单的示例图:

Alright, as mentioned in the comments above, you're going to do the matching in OLTP. That means you'll likely have a concrete entry point. Let's make up a simple sample graph:

g = TinkerGraph.open().traversal()

// Stackoverflow data
g.addV("user").property("login", "user3508638").as("a").
  addV("user").property("login", "dkuppitz").property("age", 35).as("b").
  addV("question").property("title", "Tinkerpop/gremlin merge vertices (and edges)").as("c").
  addE("posted").from("a").to("c").
  addE("commented").from("b").to("c").property("time", 123).iterate()

// Github data
g.addV("user").property("login", "dkuppitz").property("name", "Daniel Kuppitz").as("a").
  addV("project").property("title", "TinkerPop").as("b").
  addE("contributed").from("a").to("b").iterate()

根据登录名dkuppitz匹配顶点并将其合并为单个用户顶点:

To match vertices based on login dkuppitz and merge them into a single user vertex:

g.V().has("login", "dkuppitz").
  fold().filter(count(local).is(gt(1))).unfold().
  sideEffect(properties().group("p").by(key).by(value())).
  sideEffect(outE().group("o").by(label).by(project("p","iv").by(valueMap()).by(inV()).fold())).
  sideEffect(inE().group("i").by(label).by(project("p","ov").by(valueMap()).by(outV()).fold())).
  sideEffect(drop()).
  cap("p","o","i").as("poi").
  addV("user").as("u").
  sideEffect(
    select("poi").select("p").unfold().as("kv").
    select("u").property(select("kv").select(keys), select("kv").select(values))).
  sideEffect(
    select("poi").select("o").unfold().as("x").
    select("u").sideEffect { u ->
      u.path("x").getValue().each { x ->
        def e = u.get().addEdge(u.path("x").getKey(), x.get("iv"))
        x.get("p").each { p ->
          e.property(p.getKey(), p.getValue())
        }
      }
    }).
  sideEffect(
    select("poi").select("i").unfold().as("x").
    select("u").sideEffect { u ->
      u.path("x").getValue().each { x ->
        def e = x.get("ov").addEdge(u.path("x").getKey(), u.get())
        x.get("p").each { p ->
          e.property(p.getKey(), p.getValue())
        }
      }
    }).iterate()

我知道，查询非常复杂，尤其是对于嵌套很深的lambda.但不幸的是，由于我们没有addE(<traversal>)重载，因此无法绕过lambda(我创建了

I know, the query is crazy complicated, especially with the deeply nested lambdas. But unfortunately there's no way around the lambdas, since we don't have an addE(<traversal>) overload (I created a ticket though). Anyway, after executing the query above, the graph looks like this:

gremlin> g.V().valueMap()
==>[login:[user3508638]]
==>[title:[Tinkerpop/gremlin merge vertices (and edges)]]
==>[title:[TinkerPop]]
==>[name:[Daniel Kuppitz],login:[dkuppitz],age:[35]]
gremlin> g.V().has("login", "dkuppitz").bothE()
==>e[19][15-commented->5]
==>e[20][15-contributed->12]
gremlin> g.V().has("login", "dkuppitz").bothE().valueMap(true)
==>[label:commented,time:123,id:19]
==>[label:contributed,id:20]

将两个dkuppitz顶点合并为一个(具有name和age属性)，并相应地重新创建了2条边.

Both dkuppitz vertices were merged into one (name and age properties are present) and the 2 edges were recreated accordingly.

更新:

使用 TINKERPOP-1793 ，我们可以消除所有的lambda:

With TINKERPOP-1793 we can get rid of all lambdas:

g.V().has("login", "dkuppitz").
  fold().filter(count(local).is(gt(1))).unfold().
  sideEffect(properties().group("p").by(key).by(value())).
  sideEffect(outE().group("o").by(label).by(project("p","iv").by(valueMap()).by(inV()).fold())).
  sideEffect(inE().group("i").by(label).by(project("p","ov").by(valueMap()).by(outV()).fold())).
  sideEffect(drop()).
  cap("p","o","i").as("poi").
  addV("user").as("u").
  sideEffect(
    select("poi").select("p").unfold().as("kv").
    select("u").property(select("kv").select(keys), select("kv").select(values))).
  sideEffect(
    select("poi").select("o").unfold().as("x").select(values).
    unfold().addE(select("x").select(keys)).from(select("u")).to(select("iv"))).
  sideEffect(
    select("poi").select("i").unfold().as("x").select(values).
    unfold().addE(select("x").select(keys)).from(select("ov")).to(select("u"))).iterate()

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