org.apache.hadoop.examples

类 PiEstimator

java.lang.Object

org.apache.hadoop.conf.Configured

org.apache.hadoop.examples.PiEstimator

所有已实现的接口:

Configurable, Tool

public class PiEstimator
extends Configured
implements Tool

A Map-reduce program to estimate the value of Pi using quasi-Monte Carlo method. Mapper: Generate points in a unit square and then count points inside/outside of the inscribed circle of the square. Reducer: Accumulate points inside/outside results from the mappers. Let numTotal = numInside + numOutside. The fraction numInside/numTotal is a rational approximation of the value (Area of the circle)/(Area of the square), where the area of the inscribed circle is Pi/4 and the area of unit square is 1. Then, Pi is estimated value to be 4(numInside/numTotal).

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	PiEstimator.PiMapper Mapper class for Pi estimation.
static class	PiEstimator.PiReducer Reducer class for Pi estimation.

构造器概要

构造器

构造器和说明
PiEstimator()

方法概要

方法

限定符和类型	方法和说明
static BigDecimal	estimate(int numMaps, long numPoints, JobConf jobConf) Run a map/reduce job for estimating Pi.
static void	main(String[] argv) main method for running it as a stand alone command.
int	run(String[] args) Parse arguments and then runs a map/reduce job.

从类继承的方法 org.apache.hadoop.conf.Configured

getConf, setConf

从类继承的方法 java.lang.Object

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

从接口继承的方法 org.apache.hadoop.conf.Configurable

getConf, setConf

构造器详细资料

PiEstimator

public PiEstimator()

方法详细资料

estimate

public static BigDecimal estimate(int numMaps,
                  long numPoints,
                  JobConf jobConf)
                           throws IOException

Run a map/reduce job for estimating Pi.

返回:

the estimated value of Pi

抛出:

IOException

run

public int run(String[] args)
        throws Exception

Parse arguments and then runs a map/reduce job. Print output in standard out.

指定者:

run 在接口中 Tool

参数:

args - command specific arguments.

返回:

a non-zero if there is an error. Otherwise, return 0.

抛出:

Exception

main

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

main method for running it as a stand alone command.

抛出:

Exception