我想根据给定的用户偏好(用户喜欢的项目)基于使用groovy中的gremlin在有向二分图上进行随机游走来对项目进行排名。
该图具有以下基本结构:
[用户1] ---'喜欢'---> [项目A] [项目B]
此后我提出的查询:
def runRankQuery(def userVertex) {
def m = [:]
def c = 0
while (c < 1000) {
userVertex
.out('likes') // get all liked items of current or similar user
.shuffle[0] // select randomly one liked item
.groupCount(m) // update counts for selected item
.in('likes') // get all users who also liked item
.shuffle[0] // select randomly one user that liked item
.loop(5){Math.random() < 0.5} // follow liked edge of new user (feed new user in loop)
// OR abort query (restart from original user, outer loop)
.iterate()
c++
}
m = m.sort {a, b -> b.value <=> a.value}
println "intermediate result $m"
m.keySet().removeAll(userVertex.out('likes').toList())
// EDIT (makes no sense - remove): m.each{k,v -> m[k] = v / m.values().sum()}
// EDIT (makes no sense - remove): m.sort {-it.value }
return m.keySet() as List;
}
但是,此代码没有找到新项目(上面示例中的[ItemB]),但是only给定用户喜欢的项目(例如 [ItemS])。
这里是运行示例的代码:
g = new TinkerGraph()
user1 = g.addVertex()
user1.name ='User1'
user2 = g.addVertex()
user2.name ='User2'
itemA = g.addVertex()
itemA.name ='ItemA'
itemB = g.addVertex()
itemB.name ='ItemB'
g.addEdge(user1, itemA, 'likes')
g.addEdge(user2, itemA, 'likes')
g.addEdge(user2, itemB, 'likes')
println runRankQuery(user1)
和输出:
intermediate result [v[2]:1000]
[]
==>null
gremlin> g.v(2).name
==>ItemA
gremlin>