framework/helpers/BaseArrayHelper.php
public static function filter($array, $filters)
    {
        $result = [];
        $forbiddenVars = [];

        foreach ($filters as $var) {
            $keys = explode('.', $var);
            $globalKey = $keys[0];
            $localKey = isset($keys[1]) ? $keys[1] : null;

            if ($globalKey[0] === '!') {
                $forbiddenVars[] = [
                    substr($globalKey, 1),
                    $localKey,
                ];
                continue;
            }

            if (!array_key_exists($globalKey, $array)) {
                continue;
            }
            if ($localKey === null) {
                $result[$globalKey] = $array[$globalKey];
                continue;
            }
            if (!isset($array[$globalKey][$localKey])) {
                continue;
            }
            if (!array_key_exists($globalKey, $result)) {
                $result[$globalKey] = [];
            }
            $result[$globalKey][$localKey] = $array[$globalKey][$localKey];
        }

        foreach ($forbiddenVars as $var) {
            list($globalKey, $localKey) = $var;
            if (array_key_exists($globalKey, $result)) {
                unset($result[$globalKey][$localKey]);
            }
        }

        return $result;
    }
public static function filter($array, $filters)
    {
        $result = [];
        $forbiddenVars = [];

        foreach ($filters as $var) {
            $keys = explode('.', $var);
            $globalKey = $keys[0];
            $localKey = isset($keys[1]) ? $keys[1] : null;

            if ($globalKey[0] === '!') {
                $forbiddenVars[] = [
                    substr($globalKey, 1),
                    $localKey,
                ];
                continue;
            }

            if (!array_key_exists($globalKey, $array)) {
                continue;
            }
            if ($localKey === null) {
                $result[$globalKey] = $array[$globalKey];
                continue;
            }
            if (!isset($array[$globalKey][$localKey])) {
                continue;
            }
            if (!array_key_exists($globalKey, $result)) {
                $result[$globalKey] = [];
            }
            $result[$globalKey][$localKey] = $array[$globalKey][$localKey];
        }

        foreach ($forbiddenVars as $var) {
            list($globalKey, $localKey) = $var;
            if (array_key_exists($globalKey, $result)) {
                unset($result[$globalKey][$localKey]);
            }
        }

        return $result;
    }
Filters array according to rules specified.

For example:

```php
$array = [
'A' => [1, 2],
'B' => [
'C' => 1,
'D' => 2,
],
'E' => 1,
];

$result = \yii\helpers\ArrayHelper::filter($array, ['A']);
// $result will be:
// [
//     'A' => [1, 2],
// ]

$result = \yii\helpers\ArrayHelper::filter($array, ['A', 'B.C']);
// $result will be:
// [
//     'A' => [1, 2],
//     'B' => ['C' => 1],
// ]

$result = \yii\helpers\ArrayHelper::filter($array, ['B', '!B.C']);
// $result will be:
// [
//     'B' => ['D' => 2],
// ]
```

@param array $array Source array
@param array $filters Rules that define array keys which should be left or removed from results.
Each rule is:
- `var` - `$array['var']` will be left in result.
- `var.key` = only `$array['var']['key'] will be left in result.
- `!var.key` = `$array['var']['key'] will be removed from result.
@return array Filtered array
@since 2.0.9