I have a problem: nodes and nodes are connected to each other into dozens of small networks through various relationships. How can I mark each subgraph? In other words, how do I know how many subgraphs, and what are each subgraphs? Thank you very much for your help!
You may want to check out the community detection graph algorithms that come as plugins to Neo4j.
When we talk about marking subgraphs, first we'd probably look at a partition of only certain node labels and relationship types. You'd then apply the community detection to that partition, and it would assign it a community ID (just an integer really).
These algos take a bit of tuning though according to how connected the communities are and how precise you want to be. Consider it like this: at one extreme, your entire graph is always 1 community. At the other extreme, every node is its own community, nothing is quite like it. So you have to find a balance that fits for your use case.
Make sure in particular -- in the community detection algos there are multiple options. Each one has a section on "Use cases" / When to use this. Read those carefully before choosing.
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First of all, thank you very much for your help! I think I may not describe my problem: for example, there are 10,000 nodes, each 100 nodes are connected to each other to form a subgraph, the subgraph and the other subgraphs are not connected, I need to mark each subgraph. I think what I need is the Connected Components algorithm. Is my choice correct? Thank you!
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If the communities are not connected, then yes, I think connected components is probably what you want, to identify the different "islands".
thank you very much!
I have some problems when using the Connected Components algorithm: Enter the example in the official website -> cypherCALL algo.unionFind.stream('User', 'FRIEND', {})
YIELD nodeId, setId
RETURN algo.asNode(nodeId).id AS user, setId.Display ERROR:Neo.ClientError.Statement.SyntaxError
Neo.ClientError.Statement.SyntaxError: Unknown function 'algo.asNode' (line 4, column 8 (offset: 78))
"RETURN algo.asNode(nodeId).id AS user, setId"
Neo.ClientError.Statement.SyntaxError: Unknown function 'algo.asNode' (line 4, column 8 (offset: 78)) "RETURN algo.a... How do I deal with this error?
Thank you very much!
I have some problems when using the Connected Components algorithm: Enter the example in the official website -> cypherCALL algo.unionFind.stream('User', 'FRIEND', {})
YIELD nodeId, setId . I experimented many times, each time the generated setId result is different. Why is this?
I completely second this. I've built several apps where this is needed; e.g. molecule for many atoms. "Just draw a circle around the entire subgraph and mark it as an entity"
I have connect an aggregate molecule object to.... what.... the first atom? which one is first? And then cypher query starting from that (molecule)-(atom)-[:BOND*]-(atom) instead of just grabbing the subgraph. apoc not ideal, and not supported in OGMs yet.
@ruanlovelin @HashRocketSyntax Use WCC instead of apoc.subgraph: https://neo4j.com/docs/graph-data-science/1.0/algorithms/wcc/
Weakly Connected Components in the new GDS library supports consecutiveIds as an optional configuration parameter, which will label each of the components found with a consecutive integer. In addition, you can use seedProperty so that each time you run on your graph, you initialize from the existing community identifiers and re-use those labels.