Chute is a MapReduce Framework for PHP. It enables doing map reduce over iterators (Traversable) and pushes
the decision for Hadoop out into the future.
Everything starts with a MapReduce. The mapreducer binds a Mapper and Reducer together. It takes a Mapper
and a Reducer as constructor arguments.
A Mapper takes an item of data and returns it as an array looking like array($key, $values).
The key is used to group the different mapped values.
A Reducer gets two mapped values and it’s the job of the Reducer to merge them together and return a new value.
It is important that the returned value have the same structure as the given values.
Putting it all together with a CallableMapper and CallableReducer we get the following:
<?php
use Chute\MapReduce;
use Chute\Mapper\CallableMapper;
use Chute\Reducer\CallableReducer;
$mapper = new CallableMapper(function ($item) {
$isEven = $item % 2 === 0;
return [$isEven ? 'even' : 'not_even', $item];
});
$reducer = new CallableReducer(function ($item, $previous) {
return $item + $previous;
});
$mapReduce = new MapReduce($mapper, $reducer);
$resultSet = $mapReduce->run(new ArrayIterator([1, 2, 3, 4]));
The $resultSet will now contain two keys. A even and a not_even. Because the Reducer just added the values
the result for even will be 6 which is 2 + 4 and the not_even key will be 4 which is 1 + 3.
Chute is developed mainly be these wonderful people. Or they have made a significant contribution.