Online PHP editor | refs for aA826

@ 2016-06-08T16:22:54Z

<?php

$arr = array(
    2 => 'John',
    21 => 'John',
    32 => 'Joe',
    42 => 'John',
    23 => 'Joe',
    62 => 'John',
    25 => 'Joe',
    );
    
$flipped = [];
foreach($arr AS $key => $value) {
    $flipped[$value][] = $key;
}

print_r($flipped);