xshell中使用Hadoop内置的案例计算圆周率Pi怎么写
时间: 2024-11-05 21:02:24 浏览: 77
在XShell(通常指SSH客户端)中通过Hadoop进行大规模并行计算π(pi)的例子通常涉及MapReduce编程模型。这里是一个简化的步骤描述:
1. **设置环境**:
- 确保你已经安装了Hadoop(包括HDFS和YARN)并在集群上运行。
- 安装Hadoop命令行工具,如hadoop、hdfs、yarn等。
2. **编写Mapper和Reducer**:
- Mapper任务接收输入数据(比如范围内的整数对),将每个整数映射到其平方除以4的结果。
- Reducer任务接收Mapper的输出,计算所有有效项的累积值,然后通过一些数学操作得到近似的π值。
以下是伪代码示例(假设mapper.sh和reducer.sh分别为Mapper和Reducer脚本):
**Mapper.sh**
```bash
#!/bin/bash
input=$1
output=$2
for i in $input; do
echo "$i\t$i*i/4" >> $output
done
```
**Reducer.sh**
```bash
#!/bin/bash
input=$1
output=$2
sum=0
while read key value; do
sum=$(echo "scale=16; $sum + $value" | bc)
done < $input
echo "π \t $((4 * sum / input))" >> $output
```
3. **创建配置文件**:
- 创建一个job.xml文件,配置mapper和reducer的路径以及所需的其他属性。
4. **提交作业**:
```
hadoop jar hadoop-streaming.jar -mapper mapper.sh -reducer reducer.sh -input input.txt -output pi_result -file mapper.sh -file reducer.sh
```
这里`input.txt`是输入的数据源,通常是包含一系列随机生成的大范围整数对。
5. **查看结果**:
HDFS中的pi_result目录会有一个输出文件,包含π的近似值。
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