The map operator is a core method for transforming distributed datasets or RDDs in Spark. Similarly, property graphs also have three map operators defined as follows:
class Graph[VD, ED] {
def mapVertices[VD2](mapFun: (VertexId, VD) => VD2): Graph[VD2, ED]
def mapEdges[ED2](mapFun: Edge[ED] => ED2): Graph[VD, ED2]
def mapTriplets[ED2](mapFun: EdgeTriplet[VD, ED] => ED2): Graph[VD, ED2]
}Each of these methods is called on a property graph with vertex attribute type VD and edge attribute type ED. Each of them also takes a user-defined mapping function mapFun that performs one of the following:
For
mapVertices,mapFuntakes a pair of(VertexId, VD)as input and returns a transformed vertex attribute of typeVD2.For
mapEdges,mapFuntakes anEdgeobject as input and returns a transformed edge attribute of typeED2.For
mapTriplets,mapFuntakes anEdgeTripletobject as input and returns a transformed edge attribute of typeED2.