Online PHP editor | output for dUBK4

@ 2017-02-13T08:20:30Z

<?php

$rows = [
  ['cat' => 'guest', 'name' => 'name_one', 'y' => '2016', 'q' => '2', 'st' => 1],
  ['cat' => 'guest', 'name' => 'name_one', 'y' => '2017', 'q' => '3', 'st' => 2],
  ['cat' => 'guest', 'name' => 'name_two', 'y' => '2017', 'q' => '1', 'st' => 1],
  ['cat' => 'guest', 'name' => 'name_two', 'y' => '2017', 'q' => '2', 'st' => 2],
];


$data = [];
foreach ($rows as $row) {
  $link = &$data;
  foreach (['cat', 'name', 'y'] as $field) {
      if (!isset($link[$field])) $link[$field] = [];
      if (!isset($link[$field][$row[$field]])) $link[$field][$row[$field]] = [];
      $link = &$link[$field][$row[$field]];
  }
  $link[] = ['q' => $row['q'], 'st' => $row['st']];
  unset($link);
}

echo json_encode($data);

Output for 5.6.38, 7.0.0 - 7.0.31, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.4, 8.3.6: {"cat":{"guest":{"name":{"name_one":{"y":{"2016":[{"q":"2","st":1}],"2017":[{"q":"3","st":2}]}},"name_two":{"y":{"2017":[{"q":"1","st":1},{"q":"2","st":2}]}}}}}}
Output for 8.3.5: Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 {"cat":{"guest":{"name":{"name_one":{"y":{"2016":[{"q":"2","st":1}],"2017":[{"q":"3","st":2}]}},"name_two":{"y":{"2017":[{"q":"1","st":1},{"q":"2","st":2}]}}}}}}

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