Shuffle only same value associative array in PHP - php

Question

My array is
$rank = [
'20' => 1,
'30' => 1,
'40' => 2,
'50' => 2,
'60' =>3,
];
expected op
$rank = ['30' => 1,'20' => 1,'50' => 2,'40' => 2,'60' =>3];
I want ranking random means only rank 1(value) should shuffle, later rank 2 should shuffle. later 3 and so on.. how to do it this in PHP?

Answer 1

function shuffle_array($list) {
if (!is_array($list)) return $list;
$keys = array_keys($list);
shuffle($keys);
$random = array();
foreach ($keys as $key) {
$random[$key] = $list[$key];
}
return $random;
}
echo "<pre>"; print_r(shuffle_array($rank));

Answer 2

First step can be to collect all values(say roll numbers) in an array( say a set) grouped by ranks nicely.
Now, get all the unique ranks from your array.
Sort the ranks(skip this step and just run a for loop starting from 1 if ranks are sequential).
Loop over this unique ranks and get all roll numbers according to the rank in hand.
Shuffle() them and add all of them to your result.
Snippet:
<?php
function getRandomizedSortedData($ranks){
$rank_set = [];
foreach($ranks as $roll_no => $rank){
if(!isset($rank_set[ $rank ])){
$rank_set[$rank] = [];
}
$rank_set[$rank][] = $roll_no;
}
$unique_ranks = array_unique($ranks);
sort($unique_ranks);
$result = [];
foreach($unique_ranks as $rank){
$roll_nos = $rank_set[$rank];
shuffle($roll_nos);
foreach($roll_nos as $roll_no){
$result[$roll_no] = $rank;
}
}
return $result;
}
Demo: http://sandbox.onlinephpfunctions.com/code/86c0ead227a06dda5c048dc9316c53788838bd65

Answer 3

you can use php function array_filter():
$rank = [
'20' => 1,
'30' => 2,
'40' => 3,
'50' => 2,
'60' => 1,
];
function filterRank1($value) {
return $value === 1;
}
function filterRank2($value) {
return $value === 2;
}
...
$rank1 = array_filter($rank, 'filterRank1');
$rank2 = array_filter($rank, 'filterRank2');
...