PHP sort array by two field values

Question 1

I've an array like this

Array (
 [0] => Array( "destination" => "Sydney",
               "airlines" => "airline_1",
               "one_way_fare" => 100,
               "return_fare => 300
       ),
 [2] => Array( "destination" => "Sydney",
               "airlines" => "airline_2",
               "one_way_fare" => 150,
               "return_fare => 350
       ),
 [3] => Array( "destination" => "Sydney",
               "airlines" => "airline_3",
               "one_way_fare" => 180,
               "return_fare => 380
       )
)

How can i sort the value by return_fare asc , one_way_fare asc ?

I tried array_multisort() but i ended up getting mixed up data..

asort only works for one dimensional array, i need to sort by two values or more, how can i achieve this like in SQL, order by field1 asc,field2 asc ?

Question 2

array_multisort() is the correct function, you must have messed up somehow:

// Obtain a list of columns
foreach ($data as $key => $row) {
    $return_fare[$key]  = $row['return_fare'];
    $one_way_fare[$key] = $row['one_way_fare'];
}

// Sort the data with volume descending, edition ascending
array_multisort($return_fare, SORT_ASC, $one_way_fare, SORT_ASC, $data);

If you take a look at the comments at PHP's manual page for array_multisort(), you can find a very helpful array_orderby() function which allows you to shorten the above to just this:

$sorted = array_orderby($data, 'return_fare', SORT_ASC, 'one_way_fare', SORT_ASC);

To avoid the looping use array_column() (as of PHP 5.5.0):

array_multisort(array_column($data, 'return_fare'),  SORT_ASC,
                array_column($data, 'one_way_fare'), SORT_ASC,
                $data);

Question 3

usort($array['javascript']['core'], function($a, $b) {
    return $a['weight'] - $b['weight'];
});

Question 4

function cmp($a, $b)
{

$sizes = array(
"XXS" => 0,
"XS" => 1,
"S" => 2,
"M" => 3,
"L" => 4,
"XL" => 5,
"XXL" => 6
);

$asize = $sizes[$a];
$bsize = $sizes[$b];

if ($asize == $bsize) {
    return 0;
}

return ($asize > $bsize) ? 1 : -1;
}

usort($your_array, "cmp");

Question 5

You just need to change your callback function to return negative, zero or positive numbers depending on the values present (or not) in the two items being compared at any one time; just as you would when comparing a single array index in both items.

function callback($a, $b) {
    // Both have [5] so sort by that
    if ($a[5] !== '-' && $b[5] !== '-')
        return $b[5] - $a[5];

    // Neither have [5] so sort by [4]
    if ($a[5] === '-' && $b[5] === '-')
        return $b[4] - $a[4];

    // One has a [5] value
    if ($a[5] === '-')
        return 1;
    else
        return -1;
}
uasort($array, 'callback');
print_r($array);

In this particular case, the above callback could be whittled down to something like:

function callback($a, $b) {
    // Neither have [5] so sort by [4]
    if ($a[5] === '-' && $b[5] === '-')
        return $b[4] - $a[4];

    // One, or both, has a [5] value
    return $b[5] - $a[5];
}

Question 6

Use multi-byte string functions. There is a function called strcoll which seems to suit your needs.

More info:

On how to sort an array of UTF-8 strings
How to sort an array of UTF-8 strings?

EDIT: added Peter's working code, below

setlocale(LC_COLLATE, 'sk_SK.utf8');

usort($fb_friends['data'], 'custom_sort');

function custom_sort($a, $b) {
    return strcoll ($a['last_name'], $b['last_name']);
}

foreach ($fb_friends['data'] as $friend) {
    echo '<br>';
    echo $friend['name'];
}

PHP sort array by two field values

Answers

php,arrays,sorting