Sort Multi-dimensional array by decimal values

问题:

What I'm trying to do is sort a multi-dimensional array that contains decimal values. From what I've tested, floats are having trouble being ordered properly.

Array (     [0] => Array         (             [company] => Ebay             [weight] => 4.6         )      [1] => Array         (             [company] => Ebay             [weight] => 1.7         )      [2] => Array         (             [company] => Ebay             [weight] => 3.7         ) )   usort($array, 'order_by_weight');  // Sorts DESC highest first function order_by_weight($a, $b) {     return $b['weight'] - $a['weight']; } 

What is the best way to sort these numbers in descending?

回答1:

$arr = array(     array('company' => 'A', 'weight' => 4.6),     array('company' => 'B', 'weight' => 1.7),     array('company' => 'C', 'weight' => 3.7), );  usort($arr, 'order_by_weight');  function order_by_weight($a, $b) {     return $b['weight'] > $a['weight'] ? 1 : -1; }  var_dump($arr); 

PS: it's not a rocket science - this exact "trick" is used as the first example at http://php.net/usort

回答2:

You can do this with anonymous function in just one line

$arr = array(     array('company' => 'A', 'weight' => 4.6),     array('company' => 'B', 'weight' => 1.7),     array('company' => 'C', 'weight' => 3.7), ); usort($arr, function($a, $b) { return $b['weight'] > $a['weight'] ;});  print_r($arr); 

Hope this helps :)

回答3:

You can sort the array using array_multisort, altough, this is often used to sort on multiple array values instead of one.

echo "
";   $a = array(      array('company' => 'ebay', 'weight' => 4.6),       array('company' => 'ebay', 'weight' => 1.7),      array('company' => 'ebay', 'weight' => 3.7),      array('company' => 'ebay', 'weight' => 2.7),      array('company' => 'ebay', 'weight' => 9.7),      array('company' => 'ebay', 'weight' => 0.7),  );   $company = array();  $weight = array();   foreach($a as $key=>$val) {      array_push($company, $val['company']);      array_push($weight, $val['weight']);  }   array_multisort($weight, SORT_ASC, $a);   print_r($a); 

回答4:

As sorting algo here is good example for sort multi dimension array without using any more inbuilt php function

$multiarr = array('0'=>array(         "hashtag" => "a7e87329b5eab8578f4f1098a152d6f4",         "title" => "Flower",         "order" => 3),  '1' => array(         'hashtag' => "b24ce0cd392a5b0b8dedc66c25213594",         "title" => "Free",         "order" => 2), '2' => array('hashtag' => 'e7d31fc0602fb2ede144d18cdffd816b',         'title' => 'Ready',         'order' => 1     )); 

sorting function :

    function multisort (&$array, $key) { $valsort=array(); $ret=array(); reset($array); foreach ($array as $ii => $va) {     $valsort[$ii]=$va[$key]; } asort($valsort); foreach ($valsort as $ii => $va) {     $ret[$ii]=$array[$ii]; } $array=$ret; 

}

multisort($multiarr,"order")enter code here

: output :

Array  ( [2] => Array     (         [hashtag] => e7d31fc0602fb2ede144d18cdffd816b         [title] => Ready         [order] => 1     )  [1] => Array     (         [hashtag] => b24ce0cd392a5b0b8dedc66c25213594         [title] => Free         [order] => 2     )  [0] => Array     (         [hashtag] => a7e87329b5eab8578f4f1098a152d6f4         [title] => Flower         [order] => 3     ) 

)

文章来源: Sort Multi-dimensional array by decimal values