8.4. The Resource Allocation algorithm

This section describes the Resource Allocation algorithm in the Neo4j Graph Algorithms library.

Resource Allocation is a measure used to compute the closeness of nodes based on their shared neighbors.

This section includes:

8.4.1. History and explanation

The Resource Allocation algorithm was introduced in 2009 by Tao Zhou, Linyuan Lü, and Yi-Cheng Zhang as part of a study to predict links in various networks. It is computed using the following formula:

resource allocation

where N(u) is the set of nodes adjacent to u.

A value of 0 indicates that two nodes are not close, while higher values indicate nodes are closer.

The library contains a function to calculate closeness between two nodes.

8.4.2. Resource Allocation algorithm sample

The following will create a sample graph: 

MERGE (zhen:Person {name: "Zhen"})
MERGE (praveena:Person {name: "Praveena"})
MERGE (michael:Person {name: "Michael"})
MERGE (arya:Person {name: "Arya"})
MERGE (karin:Person {name: "Karin"})

MERGE (zhen)-[:FRIENDS]-(arya)
MERGE (zhen)-[:FRIENDS]-(praveena)
MERGE (praveena)-[:WORKS_WITH]-(karin)
MERGE (praveena)-[:FRIENDS]-(michael)
MERGE (michael)-[:WORKS_WITH]-(karin)
MERGE (arya)-[:FRIENDS]-(karin)

The following will return the Resource Allocation score for Michael and Karin: 

MATCH (p1:Person {name: 'Michael'})
MATCH (p2:Person {name: 'Karin'})
RETURN algo.linkprediction.resourceAllocation(p1, p2) AS score

Table 8.10. Results
score

0.5

We can also compute the score of a pair of nodes based on a specific relationship type.

The following will return the Resource Allocation score for Michael and Karin based only on the FRIENDS relationships: 

MATCH (p1:Person {name: 'Michael'})
MATCH (p2:Person {name: 'Karin'})
RETURN algo.linkprediction.resourceAllocation(p1, p2, {relationshipQuery: "FRIENDS"}) AS score

Table 8.11. Results
score

0.0

8.4.3. Syntax

The following will run the algorithm and return the result: 

RETURN algo.linkprediction.resourceAllocation(node1:Node, node2:Node, {
    relationshipQuery: null,
    direction: "BOTH"
})

Table 8.12. Parameters
Name Type Default Optional Description

node1

Node

null

no

A node

node2

Node

null

no

Another node

relationshipQuery

String

null

yes

The relationship type to use to compute similarity between node1 and node2

direction

String

BOTH

yes

The direction of relationship type to use to compute similarity between node1 and node2