README

💿 composer require dakujem/remapkeys

This package adds a pair of functions similar to array_map that are commonly used when working with arrays:

• array_remap
  • like array_map, but allows to specify/map indexes of the result
• array_map_keys
  • like array_map, but passes indexes to the iteratee function and preserves indexes in the result

Toru (alternative)

Both functions provided by this package can be replaced by utils provided by Toru 取る (dakujem/toru), which also offers tools to work with generic iterable type.

The array_remap can be replaced by less restrictive Itera::unfold:

// Original `array_remap` function call:
array_remap($function, $input);

// Replaced by `Itera` class method call:
Itera::unfold($input, $function);

Pros:

• also enable to one value into multiple
• enable including branching logic (if) inside the mapper
• may be more memory efficient, especially for large arrays

The array_map_keys can be replaced by Itera::map or Itera::apply, because all callables in Toru receive keys along with values:

// Original `array_map_keys` function call:
array_map_keys($function, $input);

// Replaced by `Itera` class method call:
Itera::map($input, $function);

Pros:

• may be more memory efficient, especially for large arrays

array_remap

Allows re-mapping both indices and values of arrays using a mapper function.

$input = [
    'foo' => 'bar',
    'b' => 'Bran',
    'unknown' => 'Stark',
];
array_remap(function($val, $index){
    return [ strtolower($val) => strlen($index) ];
}, $input);

/* result:
[
    'bar' => 3,
    'bran' => 1,
    'stark' => 7,
]
*/

$input = [
    [
        'url' => 'https://www.google.com',
        'provider' => 'Google'
    ],
    [
        'url' => 'https://www.yahoo.com',
        'provider' => 'Yahoo!'
    ],
];
array_remap(function($val){
    return [ $val['url'] => $val['provider'] ];
}, $input);

/* result:
[
    'https://www.google.com' => 'Google',
    'https://www.yahoo.com' => 'Yahoo!',
]
*/

Internally, this is a map-reduce operation.

See the source for more details.

array_map_keys

Allows to work with both array values and their indexes. The indexes are preserved in the result.

$input = [
    'foo' => 'bar',
    'boring' => 'Bran',
    'strange' => 'Stark',
];
array_map_keys(function($val, $index){
    return ucfirst($index) . ' ' . ucfirst($val);
}, $input);

/* result:
[
    'foo' => 'Foo Bar',
    'boring' => 'Boring Bran',
    'strange' => 'Strange Stark',
]
*/

Note that one could natively call array_map($values, array_keys($values)), but that call does not preserve the original keys.

See the source for more details.

Why

These two fill the gap in PHP core for commonly occurring operations when the indexes are used during mapping.
A seemingly simple task, it has its caveats when implementing, though.