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php实现mapreduce

2026-01-29 23:02:49PHP

PHP 实现 MapReduce

MapReduce 是一种用于处理大规模数据集的编程模型，通常用于分布式计算。虽然 PHP 不是 MapReduce 的原生语言，但可以通过一些库或手动实现其核心逻辑。

使用 Hadoop Streaming

Hadoop Streaming 允许用任何语言编写 MapReduce 程序，包括 PHP。

// mapper.php
<?php
while ($line = fgets(STDIN)) {
    $words = preg_split('/\s+/', trim($line));
    foreach ($words as $word) {
        echo "$word\t1\n";
    }
}
?>

// reducer.php
<?php
$counts = [];
while ($line = fgets(STDIN)) {
    list($word, $count) = explode("\t", trim($line));
    $counts[$word] = ($counts[$word] ?? 0) + $count;
}
foreach ($counts as $word => $count) {
    echo "$word\t$count\n";
}
?>

运行命令：

hadoop jar hadoop-streaming.jar \
-input input_path \
-output output_path \
-mapper mapper.php \
-reducer reducer.php

使用本地 PHP 实现

对于小规模数据，可以用纯 PHP 模拟 MapReduce。

function map($data) {
    $result = [];
    foreach ($data as $line) {
        $words = preg_split('/\s+/', trim($line));
        foreach ($words as $word) {
            $result[] = [$word, 1];
        }
    }
    return $result;
}

function reduce($mapped) {
    $counts = [];
    foreach ($mapped as $item) {
        $word = $item[0];
        $count = $item[1];
        $counts[$word] = ($counts[$word] ?? 0) + $count;
    }
    return $counts;
}

$data = ["hello world", "hello php"];
$mapped = map($data);
$result = reduce($mapped);
print_r($result);

使用第三方库

可以使用 mr-php/mr-php 等第三方库简化实现。

安装：

composer require mr-php/mr-php

示例代码：

use MRPHPSDK\MR\MapReduce;

$mapReduce = new MapReduce();
$mapReduce->map(function($line) {
    $words = preg_split('/\s+/', trim($line));
    foreach ($words as $word) {
        yield [$word, 1];
    }
})->reduce(function($key, $values) {
    return [ $key, array_sum($values) ];
})->execute(["hello world", "hello php"]);