Gremlin's request for the sum of 2 or more values
I need to write a gremlin query that can sum 2 or more properties in a set of vertices and return them as separate values.
Statement 1:
g.V().has('label1').values('p1').sum()
This will return the sum of the p1 values of all the vertices of 'label1' - say 100
Statement 2:
g.V().has('label1').values('p2').sum()
This will return the sum of the p2 values of all the vertices of 'label1' - say 200
Statement 3:
g.V().has('label1').values('p1','p2').sum()
Tried the above statement, but as expected it won't work, it will return 300, the sum of all p1 and p2 properties 'label1'
I need a query that will return the sum of p1 and the sum of p2 into one result. Perhaps there is a way that I could "collapse" or collapse a set of vertices into one vertex and aggregate the properties according to certain rules ... in my case for the sum.
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You can group all values by their key:
g.V().has("label1").properties("p1","p2").
group().by(key).by(value().sum())
EDIT
Proof that it works:
gremlin> g = TinkerGraph.open().traversal()
==>graphtraversalsource[tinkergraph[vertices:0 edges:0], standard]
gremlin> g.addV().property("p1", 1).property("p2", 10).iterate()
gremlin> g.addV().property("p1", 2).property("p2", 20).iterate()
gremlin> g.V().properties("p1", "p2").group().by(key).by(value().sum())
==>[p1:3,p2:30]
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