Adamic Adar

This section describes the Adamic Adar algorithm in the Neo4j Graph Data Science library.

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

This algorithm is in the alpha tier. For more information on algorithm tiers, see Algorithms.

1. History and explanation

The Adamic Adar algorithm was introduced in 2003 by Lada Adamic and Eytan Adar to predict links in a social network. It is computed using the following formula:

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.

2. Syntax

The following will run the algorithm and return the result:

RETURN gds.alpha.linkprediction.adamicAdar(node1:Node, node2:Node, {
    relationshipQuery:String,
    direction:String
})

Table 1. 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 used to compute similarity between `node1` and `node2`
`direction`	String	BOTH	yes	The relationship direction used to compute similarity between `node1` and `node2`. Possible values are `OUTGOING`, `INCOMING` and `BOTH`.

3. Adamic Adar algorithm sample

The following will create a sample graph:

CREATE
 (zhen:Person {name: 'Zhen'}),
 (praveena:Person {name: 'Praveena'}),
 (michael:Person {name: 'Michael'}),
 (arya:Person {name: 'Arya'}),
 (karin:Person {name: 'Karin'}),

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

The following will return the Adamic Adar score for Michael and Karin:

MATCH (p1:Person {name: 'Michael'})
MATCH (p2:Person {name: 'Karin'})
RETURN gds.alpha.linkprediction.adamicAdar(p1, p2) AS score

Table 2. Results
`score`
0.9102392266268373

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

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

MATCH (p1:Person {name: 'Michael'})
MATCH (p2:Person {name: 'Karin'})
RETURN gds.alpha.linkprediction.adamicAdar(p1, p2, {relationshipQuery: 'FRIENDS'}) AS score

Table 3. Results
`score`
0.0

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