org.apache.flink.examples.java.graph

Class PageRank

java.lang.Object

org.apache.flink.examples.java.graph.PageRank

public class PageRank
extends Object

A basic implementation of the Page Rank algorithm using a bulk iteration.

This implementation requires a set of pages and a set of directed links as input and works as follows.
In each iteration, the rank of every page is evenly distributed to all pages it points to. Each page collects the partial ranks of all pages that point to it, sums them up, and applies a dampening factor to the sum. The result is the new rank of the page. A new iteration is started with the new ranks of all pages. This implementation terminates after a fixed number of iterations.
This is the Wikipedia entry for the Page Rank algorithm.

Input files are plain text files and must be formatted as follows:

• Pages represented as an (long) ID separated by new-line characters.
  For example "1\n2\n12\n42\n63" gives five pages with IDs 1, 2, 12, 42, and 63.
• Links are represented as pairs of page IDs which are separated by space characters. Links are separated by new-line characters.
  For example "1 2\n2 12\n1 12\n42 63" gives four (directed) links (1)->(2), (2)->(12), (1)->(12), and (42)->(63).
  For this simple implementation it is required that each page has at least one incoming and one outgoing link (a page can point to itself).

Usage: PageRankBasic --pages <path> --links <path> --output <path> --numPages <n> --iterations <n>
If no parameters are provided, the program is run with default data from PageRankData and 10 iterations.

This example shows how to use:

• Bulk Iterations
• Default Join
• Configure user-defined functions using constructor parameters.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	PageRank.BuildOutgoingEdgeList A reduce function that takes a sequence of edges and builds the adjacency list for the vertex where the edges originate.
static class	PageRank.Dampener The function that applies the page rank dampening formula
static class	PageRank.EpsilonFilter Filter that filters vertices where the rank difference is below a threshold.
static class	PageRank.JoinVertexWithEdgesMatch Join function that distributes a fraction of a vertex's rank to all neighbors.
static class	PageRank.RankAssigner A map function that assigns an initial rank to all pages.

Constructor Summary

Constructors

Constructor and Description
PageRank()

Method Summary

Modifier and Type	Method and Description
static void	main(String[] args)

Methods inherited from class java.lang.Object

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

Constructor Detail

PageRank

public PageRank()

Method Detail

main

public static void main(String[] args)
                 throws Exception

Throws:

Exception