Apache TinkerPop•2mo ago

Sequential edge creation between streamed vertices

I would like to create an edge between vertices as they are streamed in sequence from a traversal. I want to connect each vertex to the next one in the stream, like a linear chain of vertices with a next edge. For example, given this g.V().hasLabel("person").values("name") produces:

==> josh
==> peter
==> marko
==> vadas

==> josh
==> peter
==> marko
==> vadas

I'd like to achieve something like josh -next-> peter -next-> marko -next-> vadas My current approach is to create a "sliding window" of vertex pairs:

g.V().
  hasLabel("person").
  aggregate(local, "a").by("name").
  map(select("a").tail(local, 2)).
  skip(1)

g.V().
  hasLabel("person").
  aggregate(local, "a").by("name").
  map(select("a").tail(local, 2)).
  skip(1)

Which results in:

==> [josh, peter]
==> [peter, marko]
==> [marko, vadas]

==> [josh, peter]
==> [peter, marko]
==> [marko, vadas]

Next I add edges between each pair:

g.V().
  hasLabel("person").
  aggregate(local, "a").
  map(select("a").tail(local, 2)).
  skip(1).
  addE("next").from(limit(local, 1)).to(tail(local, 1))

g.V().
  hasLabel("person").
  aggregate(local, "a").
  map(select("a").tail(local, 2)).
  skip(1).
  addE("next").from(limit(local, 1)).to(tail(local, 1))

This works, but I’m not sure if this is the idiomatic way to do this. I think modeling data where vertices are explicitly ordered through an edge connection is not uncommon, right?

Solution:

i think that's about as good as most approaches. we're missing a step that coudl simplify this code though. i've long wanted a partition() step so that you could change all that code to just: ``` g.V().hasLabel('person'). partition(2). addE('next').from.......

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2 Replies

Solution

spmallette•2mo ago

i think that's about as good as most approaches. we're missing a step that coudl simplify this code though. i've long wanted a partition() step so that you could change all that code to just:

g.V().hasLabel('person').
  partition(2).
  addE('next').from....

g.V().hasLabel('person').
  partition(2).
  addE('next').from....

spmallette•2mo ago

@Kelvin Lawrence do you have any other ways that you might do what's asked in this question?

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Sequential edge creation between streamed vertices