How do I traverse the graph given a start point and without knowledge of the final one?

Question

Suppose I have a graph that looks like a tree of variable arity. I have the Vertex and I don't know anything about whereabouts of the final point except that it's id is 0. I've seen some examples of the Gremlin usage, but can't find a suitable one - they all basically do something like x.out.in.out and so on, and that's inapplicable in my case. I also use the Java bindings, so I'd be grateful if your anwers came with respect to that fact.

P.S. Maybe I should be more specific. I'd also like to collect all the properties of that nodes, so if there is some kind of a reduce/foldLeft etc, but only for pipes - that'd be just great.

Answer 1

Example for the Tinkerpop Toy Graph (find a path from vadas [vertex 2] to peter [vertex 6]):

gremlin> g = TinkerGraphFactory.createTinkerGraph()
==>tinkergraph[vertices:6 edges:6]
gremlin> start = g.v(2)
==>v[2]
gremlin> end = g.v(6)
==>v[6]
gremlin> start.as("x").both().loop("x", {it.object != end}, {true}).retain([end]).path()[0]
==>[v[2], v[1], v[3], v[6]]

The query is not optimal and will run forever if you don't restrict the number of results, but it should answer your question.

If you want all properties:

gremlin> start.as("x").both().loop("x", {it.object != end}, {true}).retain([end]).path().transform({ it.collect({ it.map() }) })[0]
==>[{age=27, name=vadas}, {age=29, name=marko}, {name=lop, lang=java}, {age=35, name=peter}]

And if you just need a single property:

gremlin> start.as("x").both().loop("x", {it.object != end}, {true}).retain([end]).path().transform({ it.collect({ it.name }) })[0]
==>[vadas, marko, lop, peter]

Cheers, Daniel