- array_map: documentation ( source)
- array_chunk: documentation ( source)
- implode: documentation ( source)
<?php
$labels_array=array("Element 1","Element 2","Element 3","Element 4","Element 5","Element 6");
echo implode("\n",array_map(function($i){
return implode(", ",$i);
},array_chunk($labels_array,2)));