<?php

	$array = Array ( 
	"0" => Array ( "key1" => 1 , "key2" => 1 , "key3" => 1 , "key4" => 1 ),
	"1" => Array ( "key1" => 2 , "key2" => 2 , "key3" => 2 , "key4" => 2 ) ,
	"2" => Array ( "key1" => 3 , "key2" => 3 , "key3" => 3 , "key4" => 3 ) ,
	"3" => Array ( "key1" => 4 , "key2" => 4 , "key3" => 4 , "key4" => 4 ) );
	
	echo "<pre>";
	echo "Before", PHP_EOL ;
	print_r($array);
	
	swaparray($array,2,1);
	
	
	echo "After", PHP_EOL ;
	print_r($array);
	

	function swaparray(&$array,$originKey,$destinationKey)
	{
		$origin = $array[$originKey];
		$destination = $array[$destinationKey];
	
		$array[$originKey] = $destination ;
		$array[$destinationKey] = $origin ;
		return $array ;
	}

?>

<pre>Before
Array
(
    [0] => Array
        (
            [key1] => 1
            [key2] => 1
            [key3] => 1
            [key4] => 1
        )

    [1] => Array
        (
            [key1] => 2
            [key2] => 2
            [key3] => 2
            [key4] => 2
        )

    [2] => Array
        (
            [key1] => 3
            [key2] => 3
            [key3] => 3
            [key4] => 3
        )

    [3] => Array
        (
            [key1] => 4
            [key2] => 4
            [key3] => 4
            [key4] => 4
        )

)
After
Array
(
    [0] => Array
        (
            [key1] => 1
            [key2] => 1
            [key3] => 1
            [key4] => 1
        )

    [1] => Array
        (
            [key1] => 3
            [key2] => 3
            [key3] => 3
            [key4] => 3
        )

    [2] => Array
        (
            [key1] => 2
            [key2] => 2
            [key3] => 2
            [key4] => 2
        )

    [3] => Array
        (
            [key1] => 4
            [key2] => 4
            [key3] => 4
            [key4] => 4
        )

)