Create unique relationship property in FOREACH in neo4j
I'm trying to accomplish something pretty simple in python, but not so good in Neo4j. I would appreciate any comments and suggestions for improving the procedure!
In a Python script, I am trying to create a link as well as its property for each pair of two nodes. From parsing the data (not the csv file), I ended up with a 3-column dataframe like this:
name1 name2 points
===========================
Jack Sara 0.3
Jack Sam 0.4
Jack Jill 0.2
Mike Jack 0.4
Mike Sara 0.5
...
From now on, I would like to create all the nodes for people: Jack, Sarah, Sam, Mike, etc., and also their relationship to the property name dots.
I first tried to map all nodes and then use "FOREACH" to update the relationship property one at a time.
tx = graph.cypher.begin()
qs2 = "MATCH (p1:person {name:"Jack"}), (p2:person)
WHERE p2.name IN ["Sara","Jill","Mike"]
FOREACH (r IN range(10) |
CREATE (p1)-[:OWES TO {score:{score_list}[r]}]->(p2))"
The above statement does not return what I expected. Instead of mapping one node to another, it calls all the nodes in p2 and creates a link between paris, resulting in multiple copies of the same information.
Is there a notation to refer to one node at a time? If you think there is a better approach than the one above, please share with me. Thank!
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The easiest way is to export the import data to a csv file and use the command LOAD CSV
in cypher.
LOAD CSV WITH HEADERS FROM <url> AS csvLine
MATCH (p1:Person {name:csvLine.name1}), (p2:Person {name:csvLine.name2})
CREATE (p1)-[:OWES_TO {score:csvLine.points}]->(p2)
If you cannot use this approach, you can use the parameterized Cypher statement with a transactional http endpoint . Parameter is a single element map containing an array of your data structure. At the http level, the request body will look like this:
{
"statements": [
{
"parameters": {
"data": [
{
"name1": "Jack", "name2": "Sara", "points": 0.3
},
{
"name1": "Jack", "name2": "Sam", "points": 0.4
},
{
"name1": "Jack", "name2": "Jill", "points": 0.2
} // ...
]
},
"statement": "UNWIND {data} AS row
MATCH (p1:Person {name:row.name1}), (p2:Person {name:row.name2})
CREATE (p1)-[:OWES_TO {row.points}]->(p2)"
}
]
}
update comment below
Q: How can I create parameters from pyhton? A: use python json module
import json
json.dumps({'data':[{'name1':'Jack', 'name2':'Sara', 'points':0.3},{'name1':'Jack', 'name2':'Sam', 'points':0.4}]})
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