Creating edges in neo4j based on query results

1
votes

I'm modelling a search term transition graph in a e-commerce software as a graph of nodes (terms) and edges (transitions). If a user types e.g. iphone in the search bar and then refines the query to iphone 6s this will be modeled as two nodes and a edge between those nodes. The same transition of terms of the different users will result in several edges between the nodes.

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I'd now like to create an edge with a cumulated weight of 4 to represent that 4 users did this specific transition. How can I combine the results of a count(*) query with a create query to produce an edge with a property weight = 4

My count(*) query is:

MATCH (n:Term)-[r]->(n1:Term)
RETURN type(r), count(*)

I'd expect the combined query to look like this, but this kind of sql like composition seems not to be possible in cypher:

MATCH (n:Term), (n1:Term)
WHERE (n)-[tr:TRANSITION]->(n1)
CREATE (n)-[actr:ACC_TRANSITION {count: 
    MATCH (n:Term)-[r]->(n1:Term) RETURN 
    count(*)}
]->(n1)
RETURN n, n1

A non generic query to produce the accumulated transition that works is:

MATCH (n:Term), (n1:Term)
WHERE n.term = 'iphone' AND n1.term ='iphone 6s'
CREATE (n)-[actr:ACC_TRANSITION {count: 4}]->(n1)
RETURN n, n1

Any other ideas on how to approach and model this problem?

2
graphneo4jcypher
Use with in first query is count(*) and in second query create your relation – mastisa
Can you please formulate the query? How would it look like with the with? Thanks! – paweloque
Sorry I am busy at work and can't explain more my answer for now :) – mastisa

2 Answers

3
votes

Use WITH like this:

MATCH (n:Term)-[r]->(n1:Term)
WITH n as n, count(*) as rel_count, n1
CREATE (n)-[:ACC_TRANSITION {count:rel_count}]->(n1)
RETURN n, n1
0
votes

If you match the nodes and relationship first and then use set, you will not produce duplicate nodes or relationships

Match (n:Term)-[r]->(n1.Term)
with n as nn,count(r) as rel_count,n1 as nn1
set r.ACC_TRANSITION=rel_count
return nn,nn1,r

The create function will create duplicates.