CODEWITHSUNDEEP
gremlintinkerpop3
Denis Kirchhübel
Denis Kirchhübel

Reputation: 33

Gremlin - Select vertices based on group keys

I have a graph with 2 different vertex classes with some identical properties.

I need to:

  1. group all vertices of class Item based on some properties
  2. find the vertices of class Product that share these properties
g.addV("Item").
    property("color", "green").
    property("material", "wood").
    property("shape", "round").
    property("price", 1.2).
  addV("Item").
    property("color", "green").
    property("material", "wood").
    property("shape", "round").
    property("price", .9).
  addV("Item").
    property("color", "green").
    property("material", "wood").
    property("shape", "square").
    property("price", 5).
  addV("Product").
    property("color", "green").
    property("material", "wood").next();

What I've tried so far is this

g.V().has("Item", "price", P.inside(0, 10)).
  group().
    by(project("c", "m").
      by("color").by("material")). //\1
    local(unfold().
      project("color", "material","price","product")
        .by(select(Column.keys).select("c"))
        .by(select(Column.keys).select("m"))
        .by(select(Column.values).unfold().values("price").mean())
        .by(
          V().hasLabel("Product"). //\2
          has("material",P.eq(select(Column.keys).select("c"))).fold()));

I understand that at 2 the scope changes so select(Column.keys) no longer refers to the group. However, I'm at a loss how to get the value of the c (and m) key into the traversal at 2

Upvotes: 3

Views: 984

Answers (1)

noam621
noam621

Reputation: 2856

So I tried to solve it with a slightly different approach.

Each group will have all the items and the products for the color and material combo

that way most of the work will be done on your first group step:

g.V().coalesce(
    hasLabel("Item").has("price", P.inside(0, 10)),
    hasLabel("Product").has("color").has("material")
    ).group()
    .by(project("c", "m").by("color").by("material"))
    .unfold()
    .where(select(values).unfold().hasLabel("Item"))
      .project("color", "material","price","product")
        .by(select(keys).select("c"))
        .by(select(keys).select("m"))
        .by(select(values).unfold().hasLabel("Item").values("price").mean())
        .by(select(values).unfold().hasLabel("Product").fold())

Upvotes: 2

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