| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.crunch.scrunch.spark |
| |
| import org.apache.crunch.scrunch.{PTable, Avros} |
| import org.apache.crunch.io.{From => from} |
| |
| import _root_.org.junit.Assert._ |
| import _root_.org.junit.Test |
| |
| class PageRankTest extends CrunchSparkSuite { |
| lazy val pipeline = SparkPipeline[PageRankTest](tempDir.getDefaultConfiguration) |
| |
| def initialInput(fileName: String) = { |
| pipeline.read(from.textFile(fileName)) |
| .withPType(Avros.strings) |
| .mapWithContext((line, ctxt) => { |
| ctxt.getConfiguration; val urls = line.split("\\t"); (urls(0), urls(1)) |
| }) |
| .groupByKey |
| .map((url, links) => (url, (1.0, 0.0, links.toList))) |
| } |
| |
| def update(prev: PTable[String, (Double, Double, List[String])], d: Double) = { |
| val outbound = prev.flatMap((url, v) => { |
| val (pr, oldpr, links) = v |
| links.map(link => (link, pr / links.size)) |
| }) |
| cg(prev, outbound, d) |
| } |
| |
| def cg(prev: PTable[String, (Double, Double, List[String])], |
| out: PTable[String, Double], d: Double) = { |
| prev.cogroup(out).map((url, v) => { |
| val (p, o) = v |
| val (pr, oldpr, links) = p.head |
| (url, ((1 - d) + d * o.sum, pr, links)) |
| }) |
| } |
| |
| @Test def testPageRank { |
| var prev = initialInput(tempDir.copyResourceFileName("urls.txt")) |
| var delta = 1.0 |
| while (delta > 0.01) { |
| prev = update(prev, 0.5) |
| delta = prev.map((k, v) => math.abs(v._1 - v._2)).max.value() |
| } |
| assertEquals(0.0048, delta, 0.001) |
| pipeline.done |
| } |
| } |