README

A PHP, SQL-like stream aggregate function to group a set of rows by any number of columns. You can also define how to compute groups. Rows are expected to be already sorted on the columns used to aggregate results.

function array_aggregate(array $columns, array $rows, callable $compute_func = null): array

The order in which columns are given to the function does not affect the output. Columns must comparable with the === operator.

Inspired by Craig Freedman's SQL articles on MS dev blog https://blogs.msdn.microsoft.com/craigfr/2006/09/13/stream-aggregate.

Installation

As a composer package:

composer require micheledurante/array-aggregate

Or require the source file in src/array_aggregate.php.

Usage

$rows = [
    0 => [
        'store_id' => 1,
        'manager_id' => 2,
        'name' => 'Alice'
    ],
    1 => [
        'store_id' => 2,
        'manager_id' => 3,
        'name' => 'Bob'
    ],
    2 => [
        'store_id' => 2,
        'manager_id' => 3,
        'name' => 'Eve'
    ],
    3 => [
        'store_id' => 2,
        'manager_id' => 4,
        'name' => 'Foobar'
    ]
];

$groups = array_aggregate(array('store_id', 'manager_id'), $rows, function (array $group): array {
    return [
        'store_id' => $group[0]['store_id'],
        'manager_id' => $group[0]['manager_id'],
        'people' => implode(',', array_column($group, 'name'))
    ];
});

var_export($groups);

Results in:

/*
array (
    0 => array (
        'store_id' => 1,
        'manager_id' => 2,
        'people' => 'Alice'
    ),
    1 => array (
        'store_id' => 2,
        'manager_id' => 3,
        'people' => 'Bob,Eve'
    ),
    2 => array (
        'store_id' => 2,
        'manager_id' => 4,
        'people' => 'Foobar'
    )
)
*/

Similar Projects

array_group_by()

By jakezatecky. Main difference is that array_aggregate() won't change the structure of the array by creating new keys/nested groups. It behaves like the SQL GROUP BY clause, which returns the aggregates of the input rows. Both functions can work with multiple keys. array_aggregate() doesn't allow a callable to match columns.