README

[!IMPORTANT] This is a breaking v2 release and is not compatible with the old jotaelesalinas/php-mapreduce package. The package name, namespace, and public API have changed.

Simple in-memory map/reduce for PHP iterables.

This library is for local data processing when you want a small, readable API and do not need distributed workers, external storage, or tuning knobs. It is the lighter counterpart to heavier MapReduce-style systems.

Why this exists

• Works with any iterable, including arrays, generators, and custom iterators.
• Keeps all work inside one PHP process.
• Exposes a small fluent API that is easy to test.
• Lets you observe progress without coupling to a logger.

Install

composer require jotaelesalinas/php-simple-mapreduce

Quickstart

<?php

declare(strict_types=1);

use JLSalinas\SimpleMapReduce\MapReduce;

$result = MapReduce::create()
    ->input([1, 2, 3, 4, 5])
    ->map(static fn (mixed $item): mixed => $item * 2)
    ->reduce(static fn (mixed $carry, mixed $item): mixed => ($carry ?? 0) + $item)
    ->run();

var_dump($result);

If you prefer a reusable callable, the same pipeline works with any callable that matches the expected signature: built-ins, named functions, static methods, closures, and invokable objects:

$doublerFn = static fn (mixed $item): mixed => $item * 2;

final class Stats
{
    public static function max(?int $carry, int $item): int
    {
        return $carry === null
            ? $item
            : max($carry, $item);
    }
}

$result = MapReduce::create()
    ->input([1, 2, 3, 4, 5])
    ->map($doublerFn)
    ->reduce([Stats::class, 'max'])
    ->run();

Semantics

• input() accepts one or more iterable sources.
• The pipeline runs in this order: input, input filter, mapper, group key, mapped filter, reducer.
• filterInput() receives the raw input item and decides whether it enters the mapper.
• map() transforms each input item before reduction.
• groupBy() can group by array key, object property, or callback.
• filterMapped() receives the mapped item and, when grouping is enabled, the computed group key.
• reduce() receives the previous carry value and the mapped item.
• progress() receives the processed count, original item, and mapped item.
• output() can write reduced results to one or more Writer instances.

Fluent API

$result = MapReduce::create()
    ->input($items)
    ->filterInput($inputFilter)
    ->map($mapper)
    ->groupBy($groupBy)
    ->filterMapped($mappedFilter)
    ->reduce($reducer)
    ->progress($progressCallback)
    ->output($writer)
    ->run();

When to use this

• Use this library when you need a local, readable aggregation pipeline.
• Use a distributed engine when you need parallel workers or external storage.
• Use php-data-streams when you need specialized streaming readers and writers for formats such as CSV, JSON, XML, or xlsx.

Examples

• examples/pets.php
• examples/insurance.php
• examples/benchmark-big-dataset.php

To run the examples locally from the repository root:

composer install
php examples/pets.php
php examples/insurance.php
php examples/benchmark-big-dataset.php

Development

composer install
composer test
composer analyse
composer format

Project status

This repository is being modernized in place. The namespace, package name, and tooling have been updated; the remaining work is to keep refining the API and examples until the final plan is fully implemented.