Hi, interesting traversal... so you're saying that paths like this could be returned:
(start)-B->()-A[P=1]->()-A[P=1]->()-B->(end) but not paths like this: (start)-A[P=1]->()-B->()-A[P=2]->(end) am I correct? There are common path algorithms in GraphAlgoFactory<http://components.neo4j.org/neo4j-graph-algo/apidocs/org/neo4j/graphalgo/GraphAlgoFactory.html>but they don't support an evaluator as an argument, an evaluator which could look like: { public Evaluation evaluate( Path position ) { Relationship rel = position.lastRelationship(); if ( rel == null || !rel.isType( MyRelTypes.A ) ) return Evaluation.INCLUDE_AND_CONTINUE; Object p = rel.getProperty( "P" ); Object previousP = lookBackwardsForP( position ); if ( previousP != null && !p.equals( previousP ) ) return Evaluation.EXCLUDE_AND_PRUNE; return Evaluation.INCLUDE_AND_CONTINUE; } private Object lookBackwardsForP( Path position ) { int count = 0; for ( Relationship rel : position.relationships() ) { // Skip the first one if ( count++ > 0 ) { if ( rel.isType( MyRelTypes.A ) ) return rel.getProperty( "P" ); } } return null; } } You could probably create a breadth first traverser with such an evaluator to get your paths. I don't know about performance since each evaluation needs to go back one or more steps in the path, but you could try it out. 2010/12/23 Amos Ben Israel <lucis.domi...@gmail.com> > Hello, > > I'm trying to find all paths between two nodes when relations can be of one > of two types (A or B) without repeating the same node twice - so far quite > simple. > the complication is that relations of type A have a property P and I want > only paths where P has the same value all the way (but can have two > different values in two different paths). > I tried to have a variable that is reset every time the traverse "starts > again from the beginning" but find it difficult to know when did this > happen. position.length() helps when I only have relations of type A - it > does not ignore relations of type B which can be on the path. > iterating over the path at each position works but seems inefficient - I'd > like to hear ideas for a more efficient solution. > > Amos. > _______________________________________________ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > -- Mattias Persson, [matt...@neotechnology.com] Hacker, Neo Technology www.neotechnology.com _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
