org.apache.spark.graphx.lib

Class TriangleCount

java.lang.Object

org.apache.spark.graphx.lib.TriangleCount

public class TriangleCount
extends java.lang.Object

Compute the number of triangles passing through each vertex.

The algorithm is relatively straightforward and can be computed in three steps:

• Compute the set of neighbors for each vertex
• For each edge compute the intersection of the sets and send the count to both vertices.
• Compute the sum at each vertex and divide by two since each triangle is counted twice.

There are two implementations. The default TriangleCount.run implementation first removes self cycles and canonicalizes the graph to ensure that the following conditions hold:

• There are no self edges
• All edges are oriented src > dst
• There are no duplicate edges

However, the canonicalization procedure is costly as it requires repartitioning the graph. If the input data is already in "canonical form" with self cycles removed then the TriangleCount.runPreCanonicalized should be used instead.

 val canonicalGraph = graph.mapEdges(e => 1).removeSelfEdges().canonicalizeEdges()
 val counts = TriangleCount.runPreCanonicalized(canonicalGraph).vertices
 

Constructor Summary

Constructors

Constructor and Description
TriangleCount()

Method Summary

Methods

Modifier and Type	Method and Description
static <VD,ED> Graph<java.lang.Object,ED>	run(Graph<VD,ED> graph, scala.reflect.ClassTag<VD> evidence$1, scala.reflect.ClassTag<ED> evidence$2)
static <VD,ED> Graph<java.lang.Object,ED>	runPreCanonicalized(Graph<VD,ED> graph, scala.reflect.ClassTag<VD> evidence$3, scala.reflect.ClassTag<ED> evidence$4)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TriangleCount

public TriangleCount()

Method Detail

run

public static <VD,ED> Graph<java.lang.Object,ED> run(Graph<VD,ED> graph,
                                     scala.reflect.ClassTag<VD> evidence$1,
                                     scala.reflect.ClassTag<ED> evidence$2)

runPreCanonicalized

public static <VD,ED> Graph<java.lang.Object,ED> runPreCanonicalized(Graph<VD,ED> graph,
                                                     scala.reflect.ClassTag<VD> evidence$3,
                                                     scala.reflect.ClassTag<ED> evidence$4)