php - How can I filter values from an array and then sort them by a custom order? -

i parsing json file , have filtered out values wanted based on key loop through create variables other key values want. have sorted not sure how order displays in order want. there simplified way filter , order in 1 quick function or need order separately , if best approach?

here snippet code filtering array based on "event" key before loop. order below order in want them displayed when output too.

$str = file_get_contents($url); // put contents of file variable $o=json_decode($str,true); $features=$o['features'];  // lets filter response values want $filtered = array_filter($features,function($el){     $alerts = array('tornado warning', 'severe thunderstorm warning', 'hurricane warning', 'tropical storm warning', 'flash flood warning', 'flood warning', 'tornado watch', 'severe thunderstorm watch', 'hurricane watch', 'tropical storm watch', 'flash flood watch');      return in_array($el['properties']['event'],$alerts); }); 

use array_filter(), array_flip(), , usort():

$alerts = array(     'tornado warning',      'severe thunderstorm warning',      'hurricane warning',      'tropical storm warning',      'flash flood warning',      'flood warning',      'tornado watch',      'severe thunderstorm watch',      'hurricane watch',      'tropical storm watch',      'flash flood watch', );  // filter features, remove not of of desired event types  $alertfeatures = array_filter($features, function(array $feature) use ($alerts) {     $eventtype = $feature['properties']['event'];      return in_array($eventtype, $alerts); });  // flip alerts, mapping names of alerts index in array (we'll use order) $order = array_flip($alerts);  // sort elements order of event type desired usort($alertfeatures, function (array $a, array $b) use ($order) {     $eventtypea = $a['properties']['event'];     $eventtypeb = $b['properties']['event'];      return $order[$eventtypea] - $order[$eventtypeb]; });  var_dump($alertfeatures); 

for reference, see:

• http://php.net/manual/en/function.array-filter.php
• http://php.net/manual/en/function.array-flip.php
• http://php.net/manual/en/function.usort.php