Order array for a property

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Order array for a property

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#1 by (5 votes)
#2 by (1 votes)

8

I'm trying to sort an array by a specific property (weight), I found some possible solutions but they did not work for me, could anyone tell me where I'm doing something wrong or another way out of my need?

How am I trying to sort:

function ordenaPorPeso($a, $b) { 
    if($a->peso == $b->peso){ return 0 ; }
    return ($a->peso < $b->peso) ? -1 : 1;
} 

$arrayPaginas = array(  
            array("url" => "teste1.php", "peso" => 10),
            array("url" => "teste2.php", "peso" => 5),                      
            array("url" => "teste3.php", "peso" => 8),
            array("url" => "teste4.php", "peso" => 4),
            array("url" => "teste5.php", "peso" => 9)                     
            );

usort($arrayPaginas, 'ordenaPorPeso');

foreach($arrayPaginas as $pagina){

    echo $pagina["url"]. " - " . $pagina["peso"] . "<br /><br />";

}

Output:

teste5.php - 9

teste4.php - 4

teste3.php - 8

teste2.php - 5

teste1.php - 10

php array

asked by anonymous 19.03.2014 / 15:52

2 answers

1

As of PHP version 7 there is the spaceship operator that assists with this task.

What is the purpose of the "spaceship operator" < = > of PHP7?

It replaces the conditions (or the ternary) used in the other response :

$arrayPaginas = [  
    ["url" => "teste1.php", "peso" => 10],
    ["url" => "teste2.php", "peso" => 5],                      
    ["url" => "teste3.php", "peso" => 8],
    ["url" => "teste4.php", "peso" => 4],
    ["url" => "teste5.php", "peso" => 9]                     
];

usort($arrayPaginas, function ($a, $b) {
    return $a['peso'] <=> $b['peso'];
});

print_r($arrayPaginas);

The result will be, as expected:

Array
(
    [0] => Array
        (
            [url] => teste4.php
            [peso] => 4
        )

    [1] => Array
        (
            [url] => teste2.php
            [peso] => 5
        )

    [2] => Array
        (
            [url] => teste3.php
            [peso] => 8
        )

    [3] => Array
        (
            [url] => teste5.php
            [peso] => 9
        )

    [4] => Array
        (
            [url] => teste1.php
            [peso] => 10
        )

)

20.11.2018 / 17:01

Rails application with offline mode How / why to do variable chaining with operator = (equality)?

score 5 · Accepted Answer

The error is in the function. Each element of $arrayPaginas is an array, not an object.

Make the following correction:

function ordenaPorPeso($a, $b) { 
    if ($a['peso'] == $b['peso']) {
        return 0;
    }
    if ($a['peso'] < $b['peso']) {
        return -1;
    }
    return 1;
}

Or, in a more concise version:

function ordenaPorPeso($a, $b) { 
    return (($a['peso'] != $b['peso']) ? (($a['peso'] < $b['peso']) ? -1 : 1) : 0);
}