| /* |
| * 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.spark.examples; |
| |
| import org.apache.spark.api.java.JavaRDD; |
| import org.apache.spark.api.java.JavaSparkContext; |
| import org.apache.spark.sql.SparkSession; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * Computes an approximation to pi |
| * Usage: JavaSparkPi [partitions] |
| */ |
| public final class JavaSparkPi { |
| |
| public static void main(String[] args) throws Exception { |
| SparkSession spark = SparkSession |
| .builder() |
| .appName("JavaSparkPi") |
| .getOrCreate(); |
| |
| JavaSparkContext jsc = new JavaSparkContext(spark.sparkContext()); |
| |
| int slices = (args.length == 1) ? Integer.parseInt(args[0]) : 2; |
| int n = 100000 * slices; |
| List<Integer> l = new ArrayList<>(n); |
| for (int i = 0; i < n; i++) { |
| l.add(i); |
| } |
| |
| JavaRDD<Integer> dataSet = jsc.parallelize(l, slices); |
| |
| int count = dataSet.map(integer -> { |
| double x = Math.random() * 2 - 1; |
| double y = Math.random() * 2 - 1; |
| return (x * x + y * y <= 1) ? 1 : 0; |
| }).reduce((integer, integer2) -> integer + integer2); |
| |
| System.out.println("Pi is roughly " + 4.0 * count / n); |
| |
| spark.stop(); |
| } |
| } |