Online PHP editor | output for I060q

<?php $result = []; $compare_arr = [ ["venue1" => 1, "venue2" => 2], ["venue1" => 3, "venue2" => 4], ["venue1" => 2, "venue2" => 1], ["venue1" => 5, "venue2" => 6], ["venue1" => 7, "venue2" => 7], ["venue1" => 7, "venue2" => 7], ["venue1" => 7, "venue2" => 7], ["venue1" => 2, "venue2" => 1], ["venue1" => 2, "venue2" => 1], ["venue1" => 99, "venue2" => 200], ["venue1" => 200, "venue2" => 99], ]; foreach ($compare_arr as $v1) { sort($v1); $cKey = $v1[0] .'-'. $v1[1]; if (array_key_exists($cKey, $result)) { $result[$cKey][] = $v1; continue; } $result[$cKey] = $v1; } $result = array_filter($result, function($item) { return count($item) === 2; }); print_r($result);