How do I sort a multidimensional array by one of t

Question

Suppose I have an array that mimics a database table. Each array element represents a row, and within each row is another array that contains the field names and values.

Array
(
    [0] => Array
        (
            [name] => 'Sony TV'
            [price] => 600.00
        )

    [1] => Array
        (
            [name] => 'LG TV'
            [price] => 350.00
        )

    [2] => Array
        (
            [name] => 'Samsung TV'
            [price] => 425.00
        )  
}

What I want to do is sort the rows (outer array elements) by price. Below is an example of what I want to achieve:

Array
(
    [0] => Array
        (
            [name] => 'LG TV'
            [price] => 350.00
        )

    [1] => Array
        (
            [name] => 'Samsung TV'
            [price] => 425.00
        )

    [2] => Array
        (
            [name] => 'Sony TV'
            [price] => 600.00
        )        
}

As you can see, I don't need to preserve the keys of the outer array.

Answer 1

This question is a bit old, but will leave the answer here for future.

From php.net-Multisort function we can use the code below;

    $data= [['volume' => 67, 'edition' => 2],['volume' => 85, 'edition' => 6],...];
foreach ($data as $key => $row) {
    $volume[$key]  = $row['volume'];
    $edition[$key] = $row['edition'];
}
array_multisort($volume, SORT_DESC, $edition, SORT_ASC, $data);

The above is for a static sorting of data where you manually change sort columns.

For more dynamic and robust example consider below;

Assume I have the data below;

$data   = [[1, 'Amanda', 'Wright', '[e-mail]', 'Female', '135.114.57.89', 31237],
           [2, 'Theresa', 'Larson', '[e-mail]', 'Female', '207.108.96.210', 91011],
           [3, 'Walter', 'Kennedy', '[e-mail]', 'Male', '199.147.223.56', 50114],
           [4, 'Andrea', 'Richards', '[e-mail]', 'Female', '230.195.124.95', 76489],
           [5, 'Carol', 'Jones', '[e-mail]', 'Female', '250.197.111.90', 56501],
           [6, 'Alice', 'Freeman', '[e-mail]', 'Female', '52.195.252.131', 77170],
           [7, 'Gerald', 'Fisher', '[e-mail]', 'Male', '81.2.22.62', 75625],....]

If we need to sort the above array data out of the box, then we can set the sort orders in an array using the syntax;

 $qTable[$index]=$sort_order;
E.g. $qTable=[1=>'asc',4=>'desc',3=>'asc'];

This means sort column 1 ASC, column 4 DESC then column 3 ASC. We can then using the function below to sort our multidimension database data;

   function sortMulti($data, $orders)
    {
        $args = [];
        foreach ($data as $key => $row) {
            foreach ($orders as $index => $order) {
                if (!isset($row[$index])) continue; //Ignore if column does'nt exist
                $args[$index]['d'][$key] = $row[$index]; //Get all values within the column
                $args[$index]['o']       = 'desc' == strtolower($order) ? SORT_DESC : SORT_ASC; //Get the Sort order 'ASC' is the default
            }
        }
        $p = [];
//Below we need to organize our entries as arguments for array_multisort
        foreach ($args as $arg) {
            $p[] = $arg['d'];
            $p[] = $arg['o'];
//Below we need to check if column contains only numeric or not.
//If all values are numeric, then we use numeric sort flag, otherwise NATURAL
//Manipulate for more conditions supported
            $p[] = count($arg['d']) == count(array_filter($arg['d'], 'is_numeric')) ? SORT_NUMERIC : SORT_NATURAL;
        }
        $p[] = &$data; //Pass by reference
        call_user_func_array('array_multisort', $p); //Call Php's own multisort with parameters in required order.
        return $data; //Our final array sorted.
    }

Then we can use it as below;

$data=[[...],[...],...];
$order=[1=>'asc',4=>'desc',3=>'asc'];

$sorted=sortMulti($data,$order);

For key value array data E.g. $data=[['c1'=>1212,'c2'=>'mynames'],...]; Use the order as $order=['c1'=>'desc','c10'=>'asc'];

I tested the above with an array of 1000 records. Hope it helps someone.

Answer 2

It is just a one liner

array_multisort( array_column($yourArray, "price"), SORT_ASC, $yourArray );

You can find it here as well: http://php.net/manual/en/function.array-multisort.php

search for "array_column" on that manual page.