Graph Querying Language

Wiki page to document the syntax of the graph querying language. Most of these features will be unit tested in GraphQueriesTest.

Node collections

Definition:

val n = node[A]

Get all the instances of a node:

n()

To start querying using a custom collection:

val coll: Iterable[A] = ...
n(coll)

Edge Queries

Definition:

val n2 = node[B]
val e = edge(n,n2)

Get all neighbors of all instances of n:

n() ~> e

Get all neighbors of some of the instances of n:

n(coll) ~> e

Reverse Query, get all neighbors of all instances of n2:

n2() ~> -e

Property Queries

Definition:

val p=property[A]{
   x : A => property_sensor(x)
   }

Get the property of a specific instance x:

p(x)

It would be nicer if we can have: x.p

Composed properties:

n(x) ~> edge1 ~>edge2 p

Properties have a core which is a basic data type b, such as String, Int, etc or an Iterable[b].

Filtering Queries

Filter the instances of a node:

def f: A => Boolean = ...
n() filter f

Filter a collection of instances:

n(coll) filter f

Noe that this is different from n.filter(f) or coll.filter(f) since you can continue the graph query:

n(coll) filter f ~> e

Aggregation

• Applying a property p on a set of instances X:

node(X).p.aggregation1

• Aggregation functions:

-- Features with nominal values String aggregations, mainly concatenation

-- Integer and Real Features Numerical aggregations such as sum, multiplication, max, min, ...

Example Combinations

val n1 = node[A]
val n2 = node [B]
val n3 = node[C]

val e1 = edge(n1, n2)
val e2 = edge(n2, n3)


n1()
n1() ~> e1 // = n2
n1() ~> e1 ~> e2 // = n3

n3() ~> -e2 // = n2
n3() ~> -e2 ~> -e1 // = n1