Online PHP editor | refs for skMWu

<?php $citiesJson = <<<JSON [{"id":"AA0","name":"Aalen","region":"Süden","state":"Baden-Württemberg"}, {"id":"AB0","name":"Aschaffenburg","region":"Mitte","state":"Bayern"}, {"id":"AC0","name":"Aachen","region":"Westen","state":"Nordrhein-Westfalen"}, {"id":"WIT","name":"Witten","region":"Westen","state":"Nordrhein-Westfalen"}, {"id":"DN0","name":"Düren","region":"Westen","state":"Nordrhein-Westfalen"}] JSON; $cities = json_decode($citiesJson, true); $cities = array_map(function(array $city) { $city['city_region_state'] = sprintf( '%s, %s, %s', $city['name'], $city['region'], $city['state'] ); return $city; }, $cities); $citiesByState = array_reduce($cities, function(array $found, array $city) { $found[$city['state']][] = $city; return $found; }, []); echo json_encode($citiesByState, JSON_PRETTY_PRINT);