Select top N "ranked" values (with ties) from multidimensional array - php

Question

I want to get all rows (in descending order) which have a "score" in the top five of all scores. Because there may be ties, it is possible that there will be more than 5 rows in the result array.
I have an array in PHP :
Array
(
[0] => Array([number] => 1162)
[1] => Array([number] => 1162)
[2] => Array([number] => 1158)
[3] => Array([number] => 1157)
[4] => Array([number] => 1157)
[5] => Array([number] => 1130)
[6] => Array([number] => 1117)
[7] => Array([number] => 1097)
[8] => Array([number] => 1086)
)
I want the rows with the top 5 ranks. The final output contains 7 rows because of ties:
Array
(
[0] => Array([number] => 1162) #1 Rank
[1] => Array([number] => 1162) #1 Rank
[2] => Array([number] => 1158) #2 Rank
[3] => Array([number] => 1157) #3 Rank
[4] => Array([number] => 1157) #3 Rank
[5] => Array([number] => 1130) #4 Rank
[6] => Array([number] => 1117) #5 Rank
)
How can I achieve this? This array value data can be changed according to the situation.

Answer 1

You first need to order the array Desc. Adjust how much ranking you want using the variable $limit.
<?php
$limit = 5;
$arr = array();
$arr[] = array('number' => 1162);
$arr[] = array('number' => 1162);
$arr[] = array('number' => 1158);
$arr[] = array('number' => 1157);
$arr[] = array('number' => 1157);
$arr[] = array('number' => 1130);
$arr[] = array('number' => 1117);
$arr[] = array('number' => 1097);
$arr[] = array('number' => 1086);
function sortByOrder($a, $b) {
return $b['number'] - $a['number'];
}
function searchForId($id, $array) {
foreach ($array as $key => $val) {
if ($val['number'] === $id) {
return true;
}
}
return false;
}
usort($arr, 'sortByOrder');
$new_arr = array();
$i = 0;
foreach($arr as $key => $value){
$checkDuplicate = searchForId($value['number'], $new_arr);
if(!$checkDuplicate){
$i++;
}
if($i > $limit){
break;
}
$new_arr[] = $value;
}
var_dump($new_arr);
Result:
array(7) {
[0]=>
array(1) {
["number"]=>
int(1162)
}
[1]=>
array(1) {
["number"]=>
int(1162)
}
[2]=>
array(1) {
["number"]=>
int(1158)
}
[3]=>
array(1) {
["number"]=>
int(1157)
}
[4]=>
array(1) {
["number"]=>
int(1157)
}
[5]=>
array(1) {
["number"]=>
int(1130)
}
[6]=>
array(1) {
["number"]=>
int(1117)
}
}
Demo: https://sandbox.onlinephpfunctions.com/c/49751

Answer 2

Because you array of rows are consistently formatted, you can simply call rsort() to natively sort the data in a descending fashion.
Next iterate the sorted array and maintain an incremented "counter" variable ($rank) -- only increase this value when a new $number is encountered. So long as the rank of the current number is less than on equal to the $maxRank, push the $number into the result array. In other words, when the current rank exceeds the max rank, do not push any more numbers into the result and stop iterating.
Code: (Demo)
$array = [
['number' => 1117],
['number' => 1097],
['number' => 1162],
['number' => 1158],
['number' => 1162],
['number' => 1157],
['number' => 1086],
['number' => 1157],
['number' => 1130],
];
$maxRank = 5;
rsort($array); // sort DESC
$rank = 0;
$result = [];
foreach ($array as ['number' => $number]) {
$ranks[$number] ??= ++$rank;
if ($ranks[$number] > $maxRank) {
break;
}
$result[] = $number;
}
var_export($result);
Output:
array (
0 => 1162,
1 => 1162,
2 => 1158,
3 => 1157,
4 => 1157,
5 => 1130,
6 => 1117,
)
To see how the ranks are distributed without the break, see this demo.