public function testExtract()
{
$expected = array('a' => 'ai', 'b' => 'bi', 'd' => 'ai');
$this->assertEquals($expected, Arr::extract($this->input, 'i'));
$expected = array('b' => 'bk', 'd' => 'dk');
$this->assertEquals($expected, Arr::extract($this->input, 'k'));
}
/**
* Create an array of child values specified by a key in a 2D array.
* @param mixed $field
* @return Arr
*/
public function extract($key)
{
return new self(Arr::extract($this->data, $key));
}