How to select random vertices in Gremlin

Question

I'm still at my earlier stages with graphs and gremlin.

Is it possible to randomly select graph vertices in Gremlin?

Consider the following pipeline that gets the cars owned by a user's friend:

u.out('Friend')[0..9].out('Drives').map()

But this code is only executed against the first 10 friends every time. How can I make the selection random efficiently?

Thank you for your time :)

Seems we could create a general purpose pipe that takes the desired number of elements as an argument and iterates through all input and then returns that number of randomly selected elements. — Paul Jackson, Feb 25 '15 at 15:19

stephen mallette · Answer 1 · 2016-08-26T10:19:45.293

6

In Gremlin 2.x you could use random step as in:

g.v(1).out.random()

or in 3.x random has become coin:

as in:

g.V(1).out.coin()

in 3.x, you might also look at sample and order(shuffle) steps in 3.x.

edited Aug 26 '16 at 10:19

answered Feb 25 '15 at 15:19

stephen mallette

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score 1 · Accepted Answer · edited May 23 '17 at 11:53

You could use shuffle:

 g = TinkerGraphFactory.createTinkerGraph()
 gremlin> g.v(1).out.shuffle[0]
 ==>v[3]
 gremlin> g.v(1).out.shuffle[0]
 ==>v[2]
 gremlin> g.v(1).out.shuffle[0]
 ==>v[3]
 gremlin> g.v(1).out.shuffle[0]
 ==>v[4]

This solution isn't very efficient though since all neighbours of v(1) need to be fetched.

This might help as well: Random Walk on Bipartite Graph with Gremlin

How to select random vertices in Gremlin

2 Answers2