Yii2.0 ArrayHelper::map() usage method

Construct a mapping (in the form of key-value) from a multidimensional array or array

The mapping relationship is set by specifying the corresponding key value or attribute name through the "$from" and "$to" parameters.

Of course, you can also further group mapping based on the grouping field "$group".

For example:

$array = [

['id' => '123', 'name' => 'aaa', 'class' => 'x'],

['id' => '124', 'name' => 'bbb', 'class' => 'x'],

['id' => '345', 'name' => 'ccc', 'class' => 'y'],

];

The above array executes the following method

还可以添加第四个参数  
  
$result = ArrayHelper::map($array, 'id', 'name', 'class');

The result is

[

'x' => [

'123' => 'aaa',

'124' => 'bbb',

],

'y' => [

'345' => 'ccc',

],

]

The following is the detailed code of the map method

/**
* @paramarray $array
* @param string|Closure $from
* @param string|Closure $to
* @param string|Closure $group
* @return array
*/
public static function map($array, $from, $to, $group = null)
{
$result = [];
foreach ($array as $element) {
$key = static:: getValue($element, $from);
$value = static:: getValue($element, $to);
if ($group !== null) {
$result[ static:: getValue($element, $group)][$key] = $value;
} else {
$result[$key] = $value;
}
}
return $result;
}