Question

我正在运行Neo4j 3.4.1。我运行了一个聚类算法，并创建了带有标签“ labelpart”的聚类。现在，我想为每个群集找到中间度中心度最高的节点。我可以针对特定的cluster_id（例如3212

）运行以下查询

CALL algo.betweenness.stream(
  'MATCH (p {labelpart:3212}) RETURN id(p) as id',
  'MATCH (p1 {labelpart:3212})-[]->(p2 {labelpart:3212}) RETURN id(p1) as source, id(p2) as target',
  {graph:'cypher', write: false}
) YIELD nodeId, centrality
RETURN nodeId,centrality order by centrality desc limit 1

现在，我想以编程方式对所有群集ID进行操作。我使用针对Python的neo4j螺栓驱动程序尝试了以下查询：

from neo4j import GraphDatabase, basic_auth

这是查询

cluster_id = 3212
query = """
CALL algo.betweenness.stream(
  'MATCH (p {labelpart:{cluster_id}}) RETURN id(p) as id',
  'MATCH (p1 {labelpart:{cluster_id}})-[]->(p2 {labelpart:{cluster_id}}) RETURN id(p1) as source, id(p2) as target',
  {graph:'cypher', write: false}
) YIELD nodeId, centrality
RETURN nodeId,centrality order by centrality desc limit 1
"""
results = session.run(query, parameters = {'cluster_id':cluster_id })

我收到以下错误消息

....
ClientError: Failed to invoke procedure `algo.betweenness.stream`: Caused by: org.neo4j.cypher.ParameterNotFoundException: Expected parameter(s): cluster_id

使用参数可用于简单查询，例如我可以执行以下操作

cluster_id = 3212
query1 = """
MATCH (p {labelpart:{cluster_id}}) RETURN id(p) as id
"""
results = session.run(query1, parameters = {'cluster_id':cluster_id })

现在，我的问题是我需要提交参数的查询本身就是algo.betweenness.stream（）函数的参数。

不幸的是，我找不到有关如何为此类查询提交参数的任何说明。也许只是不可能？

Answer 1

@David，您的猜测是正确的。

您需要编写如下查询：

query = """ CALL algo.betweenness.stream(   'MATCH (p {labelpart:{cluster_id}}) 
 RETURN id(p) as id',
 'MATCH (p1 {labelpart:{cluster_id}})-[]->(p2 {labelpart:{cluster_id}}) RETURN id(p1) 
as source, id(p2) as target',
{graph:'cypher', write: false, params:{cluster_id:{ext_parameter_name}}}
) YIELD nodeId, centrality RETURN nodeId,centrality order by
centrality desc limit 1 """

ext_parameter_name 是session.run的参数。（使用其他名称以避免混淆）。

在neo4j算法查询中提交参数

1 个答案: