package org.lujinhong.demo.spark

/*

 * 官方的sparkPi示例

 */

import scala.math.random

import org.apache.spark._

/** Computes an approximation to pi */

object SparkPi {

  def main(args: Array[String]) {

    val conf = new SparkConf().setAppName("Spark Pi").setMaster("local")

    val spark = new SparkContext(conf)

    val slices = if (args.length > 0) args(0).toInt else 2

    val n = math.min(100000L * slices, Int.MaxValue).toInt // avoid overflow

    val count = spark.parallelize(1 until n, slices).map { i =>

      val x = random * 2 - 1

      val y = random * 2 - 1

      if (x*x + y*y < 1) 1 else 0

    }.reduce(_ + _)

    println("Pi is roughly " + 4.0 * count / n)

    spark.stop()

  }

}