Enhancing asort by order of keys - php

Question

I am using asort to sort the numeric array. For e.g.
$arr = [0,1,1,2,1,2,2,3];
After running asort I am getting:
Array
(
[0] => 0
[4] => 1
[2] => 1
[1] => 1
[6] => 2
[3] => 2
[5] => 2
[7] => 3
)
But I am expecting to get it in this order:
Array
(
[0] => 0
[1] => 1
[2] => 1
[4] => 1
[3] => 2
[5] => 2
[6] => 2
[7] => 3
)
See the difference in order of the keys above.

Answer 1

First sort the array.
Then generate an array by flipping in a way so that the keys can be separated according to values. Sort the arrays with keys and merge them to an array. And the combine the keys with the sorted values.
$arr = [0,1,1,2,1,2,2,3];
asort($arr);
$sorted = $arr;
$flipped = $new_keys = array();
foreach($arr as $key => $val) {
$flipped[$val][] = $key; // Get the keys
}
foreach($flipped as $key => $val_array) {
asort($val_array); // Sort the keys
$new_keys = array_merge($new_keys, $val_array);
}
$final = array_combine($new_keys, $sorted); // Combine them again
var_dump($final);
Output
array(8) {
[0]=>
int(0)
[1]=>
int(1)
[2]=>
int(1)
[4]=>
int(1)
[3]=>
int(2)
[5]=>
int(2)
[6]=>
int(2)
[7]=>
int(3)
}

Answer 2

This should work for you:
First walk through each array value with array_walk() and change each value to an array containing the value and the key.
After this use uasort() to sort your array and if both values are the same you use the key to choose which one should be first.
At the end just use array_column() to transform your array back.
<?php
$arr = [0,1,1,2,1,2,2,3];
array_walk($arr, function(&$v, $k){
$v = ["value" => $v, "key" => $k];
});
uasort($arr, function($a, $b){
if($a["value"] == $b["value"]) {
if($a["key"] == $b["key"])
return 0;
return $a["key"] > $b["key"] ? 1 : -1;
}
return $a["value"] > $b["value"] ? 1 : -1;
});
$arr = array_column($arr, "value", "key");
print_r($arr);
?>
output:
Array
(
[0] => 0
[1] => 1
[2] => 1
[4] => 1
[3] => 2
[5] => 2
[6] => 2
[7] => 3
)