3v4l.org

run code in 300+ PHP versions simultaneously
<?php $json = '[{ "id": 1, "time": "2018-12-16", "pages_indexed": 1024 }, { "id": 2, "time": "2018-12-12", "something": 1024 }, { "id": 3, "time": "2018-12-09", "something": 7 }, { "id": 12, "time": "2018-11-12", "something": 7 }, { "id": 13, "time": "2018-11-08", "something": 7 }]'; $items = json_decode($json, true); $expectedArray = []; foreach ($items as $item) { $indexKey = substr($item['time'], 0, 7); if (!isset($expectedArray[$indexKey]) || $expectedArray[$indexKey]['time'] < $item['time']) $expectedArray[$indexKey] = $item; } print_r(json_encode($expectedArray));

preferences:
13.54 ms | 402 KiB | 5 Q