Manipulating multidimensional array in PHP? - php

Question

array(2) {
[0]=>
object(stdClass)#144 (2) {
["id"]=>
string(1) "2"
["name"]=>
string(5) "name1"
}
[1]=>
object(stdClass)#145 (2) {
["id"]=>
string(1) "4"
["name"]=>
string(5) "name2"
}
}
I want to add key and value (for example [distance] = 100;) to the objects in the array. After this I want to sort on the distance values. How can I achieve this?

Answer 1

To get structure such as yours you can do:
$arr = array();
$arr[0]->id = "2";
$arr[0]->name = "name1";
$arr[1]->id = "4";
$arr[1]->name = "name2";
To add "distance" you can do:
$arr[0]->distance = 100;
$arr[1]->distance = 200;
To sort you can use decorate/sort/undecorate pattern:
$arr = array_map(create_function('$o', 'return array($o->distance, $o);'), $arr); // transform array of objects into array of arrays consisted of sort key and object
sort($arr); // sort array of arrays
$arr = array_map('end', $arr); // take only last element from each array
Or you can use usort() with custom comparison function like this:
function compareDistanceFields($a, $b) {
return $a->distance - $b->distance;
}
usort($arr, "compareDistanceFields");

Answer 2

$my_array[0]->distance = 100;
$my_array[0]->distance = 101;
usort($my_array, "cmp");
function cmp($a, $b)
{
if ($a->distance == $b->distance)
return 0;
return ($a->distance > $b->distance) ? 1: -1;
}

Answer 3

What you have here is an array of hashes; that is, each element of your array is a hash (a structure containing elements, each of which is identified by a key).
In order to add a key and value, you just assign it, like this:
$array[0]["distance"]=100;
$array[1]["distance"]=300;
#and so on
PHP hashes and arrays in general are documented here.
Now, in order to sort your array (each of whose elements is a hash), you need to use the "uasort" function, which allows you to define a comparison function; in this comparison function you define the behavior you want, which is sorting on the value of the distance key.
Something like this:
// Comparison function, this compares the value of the "distance" key
// for each of the two elements being compared.
function cmp($a, $b) {
if ($a["distance"] == $b["distance"]) {
return 0;
}
return ($a["distance"] < $b["distance"]) ? -1 : 1;
}
Once this is defined, you call uasort like this:
uasort($array, 'cmp');
Find more documentation on uasort here.