<?php

$array1 = array(
0 => "bar",
"cat" => "foo",);
foreach($array1 as $key => $value)
{
 $array1[$value] = $value;
 unset($array1[$key]);
}

var_dump($array1);

array(2) {
  ["bar"]=>
  string(3) "bar"
  ["foo"]=>
  string(3) "foo"
}