Connected Component in JanusGraph

[Antriksh Shah]

1)For an existing graph, I want to perform label propagation algorithm. 

To simplify it furthur, for a given vertex V; update a specific property for all vertices connected to V directly or transitively via any edge.

Currently I am using the query- 

graph.traversal().V(vertex).repeat(both()).until(cyclicPath()).both().dedup().property("label","new_label")

Is there a faster way to do this? 

2)Also once I have update the data, I want to get all vertices whose label have been updated from the above command and write it back to a relational database as well.

For that I am  doing

Iterator iter = graph.traversal().V(vertex).repeat(both()).until(cyclicPath()).both().dedup().valueMap("property_key", "label");

Then iterating over each vertex that I received I write it back to the database.

At times if the graph is too dense, I get a heap size exceeded exception in trying to store all graphs in iterator.

Is there any optimised way to run this faster? 

My code is in java.

Any help or suggestions, very greatly appreciated. Thank you in advance.

[Daniel Kuppitz]

This can all be done in a single run, you don't even have to enable path computations.

g.V(vertex).
  repeat(both().dedup()).
    emit().
  or(hasNot("foo"), has("foo", neq("bar"))).
  property("foo", "bar")

The result will already contain all vertices that were updated. Just note, that you can't change the label of a vertex, but if "label" is a property in your case, then it's all good.

Example:

gremlin> g = TinkerFactory.createModern().traversal()

==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]

gremlin> g.V(3).property("foo","bar").iterate() // now v[3] will not appear in the result as its 'foo' value won't be updated

gremlin> g.V(1).

           repeat(both().dedup()).

             emit().

           or(hasNot("foo"), has("foo", neq("bar"))).

           property("foo", "bar")

==>v[2]

==>v[4]

==>v[1]

==>v[6]

==>v[5]

Cheers,

Daniel

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[Antriksh Shah]

Hey daniel,

I tried the above query, but it is not covering all the vertices of a given component.

This question was in reference to this one. https://groups.google.com/forum/#!topic/janusgraph-users/NmwZyag1w2M

Thanks for the help!

Also if it is not too much trouble, could you have a look at this question as well? It is related to this question.

https://groups.google.com/forum/#!topic/janusgraph-users/NmwZyag1w2M

Somebody has replied saying it is not possible to find connected components for a fully connected graph of 35 vertices.

Thanks again!

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