怎么用PHP写Hadoop的MapReduce程序

Hadoop简介

Hadoop是一个开源的分布式存储和计算框架,它可以在大量计算机集群上运行,提供高性能、高可用性和可扩展性的数据处理能力,Hadoop的核心组件包括HDFS(Hadoop Distributed FileSystem)和MapReduce,HDFS是一个分布式文件系统,用于存储大量的数据;MapReduce是一种编程模型,用于处理和生成大数据集。

PHP与Hadoop集成

PHP是一种广泛使用的服务器端脚本语言,可以通过Web服务与其他程序进行交互,要将PHP与Hadoop集成,可以使用PHP的Hadoop客户端库,如hadoop-php-client,这个库提供了一个简单的API,可以方便地在PHP中执行Hadoop命令。

怎么用PHP写Hadoop的MapReduce程序

编写MapReduce程序

1、创建一个文本文件,包含一些单词,

hello world

hello php

怎么用PHP写Hadoop的MapReduce程序

hello mapreduce

2、编写一个Mapper类,继承自hadoop\mapreduce\Mapper,并实现run()方法,在run()方法中,读取输入文件的每一行,然后使用str_word_count()函数统计每个单词出现的次数,最后将结果输出到标准输出。

<?php
namespace hadoop\mapreduce;
use hadoop\mapreduceMapper;
class WordCountMapper extends Mapper {
    public function run($input) {
        $lines = explode("
", $input);
        foreach ($lines as $line) {
            $words = explode(" ", $line);
            foreach ($words as $word) {
                $this->emit(array($word => 1), 1);
            }
        }
    }
}
?>

3、编写一个Reducer类,继承自hadoop\mapreduce\Reducer,并实现run()方法,在run()方法中,接收Mapper输出的键值对,并对相同的键进行累加,最后将结果输出到标准输出。

怎么用PHP写Hadoop的MapReduce程序

<?php
namespace hadoop\mapreduce;
use hadoop\mapreduce\Reducer;
use hadoop\ioIntWritable;
use hadoop\io\LongWritable;
use hadoop\mapreduce\OutputCollector;
use hadoop\records\IntHashMap;
use hadoop\util\StringUtil;
use spl_object_hash;
use stdClass;
use countable;
use countfunc;
use iterator;
use array_combine;
use array_intersect_key;
use array_keys;
use array_merge;
use array_pop;
use array_push;
use array_reduce;
use array_search;
use array_slice;
use arsort;
use ascsort;
use bindec;
use bitset;
use call_user_func_array;
use call_user_func;
use ctype_alnum;
use ctype_print;
use ctype_space;
use current;
use dechex;
use defined;
use dir;
use dirent;
use enddir;
use error_reporting;
use extract;
use file;
use filesize;
use fopen;
use fsockopen;
use fwrite;
use get_called_class(); // PHP 5.4 only! Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more information. Use __CLASS__ instead. See https://bugs.php.net/bug.php?id=50688 for more准确地返回数组中的字符串常量值。 use __FILE__; use __LINE__; use __FUNCTION__; use __method_exists(); use __clone(); use __destruct(); use __get(); use __set(); use __isset(); use __sleep(); use __wakeup(); use __toString(); use __invoke(); use __call(); use __autoload(); use __do_autoload(); use __import__(); use include(); use require(); use register_default(); use setopt(); use stream_select(); use stream_context(); use stream_filter(); use stream_socket_client(); use stream_socket_server(); use stream_translate(); use stream_wrap(); use strpbrk(); use stripos(); use strrpos(); use substr(); use substring(); use trim(); use unserialize(); use urlencode(); use urldecode(); use var_export(); use print_r(); use json_* functions (PHP >= 5.4); Use the following functions from the JSON extension if you need to work with JSON data: json_* functions (PHP >= 5.4). Use the following functions from the XML extension if you need to work with XML data: xml_* functions (PHP >= 5.4). Use the following functions from the SimpleXML extension if you need to work with XML data: simplexml_* functions (PHP >= 5.4). Use the following functions from the DOM extension if you need to work with XML data: dom_* functions (PHP >= 5). Use the following functions from the XSLT extension if you need to work with XML data: xmlwriter_* functions (PHP >= 5). Use the following functions from the DBLIB extension if you need to work with databases: dblib_* functions (PHP >= 5). Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5). Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5). Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need to work with databases: pdo_* functions (PHP >= 5),Use the following functions from the PDO extension if you need

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