Apache Spark Graph Processing by Unknown

Author:Unknown
Language: eng
Format: epub, mobi
Publisher: Packt Publishing

Transforming the vertex and edge attributes

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, mapFun takes a pair of (VertexId, VD) as input and returns a transformed vertex attribute of type VD2.

For mapEdges, mapFun takes an Edge object as input and returns a transformed edge attribute of type ED2.

For mapTriplets, mapFun takes an EdgeTriplet object as input and returns a transformed edge attribute of type ED2.

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