Sort and shuffle multidimensional array - php

Question

I am working on gaming project, which needs sort and shuffle multidimensional array. First i need to sort based on bid. If multiple bids are same i need to sort based on priority. If bid & priority both are same means I need to shuffle those elements. For example we have 3 array elements in bid=0.4 & priority=4. Id's are 102,103 & 104. These array element position should be shuffled.
array(
array('id' => 101, 'bid' => 0.5, 'priority' => 5),
array('id' => 102, 'bid' => 0.4, 'priority' => 4),
array('id' => 103, 'bid' => 0.4, 'priority' => 4),
array('id' => 104, 'bid' => 0.4, 'priority' => 4),
array('id' => 105, 'bid' => 0.3, 'priority' => 5),
array('id' => 106, 'bid' => 0.3, 'priority' => 5),
array('id' => 107, 'bid' => 0.2, 'priority' => 5),
array('id' => 108, 'bid' => 0.7, 'priority' => 5),
array('id' => 108, 'bid' => 0.1, 'priority' => 4)
);

Answer 1

You should take a look at array_multisort to do that. There are examples on that page on how to sort a multi-dimensional array
<?php
// Obtain a list of columns
foreach ($data as $key => $row) {
$bid[$key] = $row['bid'];
$prio[$key] = $row['priority'];
}
array_multisort($bid, SORT_ASC, $prio, SORT_ASC, $data);
?>
To shuffle I would add an extra column to the multidimensional array called "rand" and then fill it with a random number before you use multisort. Then you can add a 3th sort order on that column for shuffling.

Answer 2

Based on idea #Hugo's answer about using random weight:
$array = array(
array('id' => 101, 'bid' => 0.5, 'priority' => 5),
array('id' => 102, 'bid' => 0.4, 'priority' => 4),
array('id' => 103, 'bid' => 0.4, 'priority' => 4),
array('id' => 104, 'bid' => 0.4, 'priority' => 4),
array('id' => 105, 'bid' => 0.3, 'priority' => 5),
array('id' => 106, 'bid' => 0.3, 'priority' => 5),
array('id' => 107, 'bid' => 0.2, 'priority' => 5),
array('id' => 108, 'bid' => 0.7, 'priority' => 5),
array('id' => 108, 'bid' => 0.1, 'priority' => 4)
);
function cmp(&$a, &$b) { # notice the use of & in function signature
if ($a['bid'] - $b['bid']) {
return $a['bid'] - $b['bid'] > 0 ? 1 : -1; # bid is different, sort using bid
} else if ($a['priority'] - $b['priority']) {
return $a['priority'] - $b['priority'] > 0 ? 1 : -1; # priority is different, sort using priority
} else {
if (isset($a['rw']) == false) {
$a['rw'] = rand(1, 100); # assign random tie breaker
}
if (isset($b['rw']) == false) {
$b['rw'] = rand(1, 100); # assign random tie breaker
}
if ($a['rw'] - $b['rw']) {
return $a['rw'] - $b['rw'] > 0 ? 1 : -1; # sort using random weight
} else {
return 0;
}
}
}
usort($array, 'cmp');
var_dump($array);
Output
array(9) {
[0]=>array(3) {["id"]=>int(108) ["bid"]=>float(0.1) ["priority"]=>int(4)}
[1]=>array(3) {["id"]=>int(107) ["bid"]=>float(0.2) ["priority"]=>int(5)}
[2]=>array(4) {["id"]=>int(106) ["bid"]=>float(0.3) ["priority"]=>int(5) ["rw"]=>int(70)}
[3]=>array(4) {["id"]=>int(105) ["bid"]=>float(0.3) ["priority"]=>int(5) ["rw"]=>int(73)}
[4]=>array(4) {["id"]=>int(103) ["bid"]=>float(0.4) ["priority"]=>int(4) ["rw"]=>int(29)}
[5]=>array(4) {["id"]=>int(104) ["bid"]=>float(0.4) ["priority"]=>int(4) ["rw"]=>int(67)}
[6]=>array(4) {["id"]=>int(102) ["bid"]=>float(0.4) ["priority"]=>int(4) ["rw"]=>int(80)}
[7]=>array(3) {["id"]=>int(101) ["bid"]=>float(0.5) ["priority"]=>int(5)}
[8]=>array(3) {["id"]=>int(108) ["bid"]=>float(0.7) ["priority"]=>int(5)}
}

Answer 3

Usort would be ideal for this situation http://www.php.net/manual/en/function.usort.php
You define the function that does the comparisons
<?php
function cmp($a, $b)
{
if ($a['bid'] == $b['bid']) {
if ($a['priority'] == $b['priority']) return 0;
return ($a['priority'] < $b['priority']) ? -1 : 1;
}
return ($a['bid'] < $b['bid']) ? -1 : 1;
}
usort($data, "cmp");
?>

Answer 4

Also based on #Hugos answer, adding shuffle using PHP built in shuffle() and range() functions:
<?php
$data=array(
array('id'=>101,'bid'=>0.5,'priority'=>5),
array('id'=>102,'bid'=>0.4,'priority'=>4),
array('id'=>103,'bid'=>0.4,'priority'=>4),
array('id'=>104,'bid'=>0.4,'priority'=>4),
array('id'=>105,'bid'=>0.3,'priority'=>5),
array('id'=>106,'bid'=>0.3,'priority'=>5),
array('id'=>107,'bid'=>0.2,'priority'=>5),
array('id'=>108,'bid'=>0.7,'priority'=>5),
array('id'=>108,'bid'=>0.1,'priority'=>4)
);
$rand=range(0,count($data)-1);
shuffle($rand);
foreach ($data as $key => $row) {
$bid[$key] = $row['bid'];
$prio[$key] = $row['priority'];
}
array_multisort($bid, SORT_ASC, $prio, SORT_ASC, $rand, SORT_ASC, $data);
I first tried simply shuffling the array before sorting, but for some unknown reason, sorting seems to sort on id as well. Probably some effect of algorithm used.

Answer 5

You can use usort
usort($array,function ($a, $b) {
if ($a['id'] == $b['id']) {
if ($a['priority'] == $b['priority'] && $a['bid'] == $b['bid']) {
$pos = array(-1,0,1);
return $pos[mt_rand(0, 2)]; // shurffle
}
$a = $a['priority'];
$b = $b['priority'];
return ($a == $b) ? 0 : (($a > $b) ? - 1 : 1); // sorty by priority
}
// First i need to sort based on bid
$a = $a['id'];
$b = $b['id'];
return ($a == $b) ? 0 : (($a < $b) ? - 1 : 1); //sort by bid id
});

Answer 6

<?php
foreach ($data as $key => $row) {
//just create a random field
$data[$key]['randSort']= rand(1,999999);
$sameRand[$key] = $data[$key]['randSort'];
$bid[$key] = $row['bid'];
$prio[$key] = $row['priority'];
}
array_multisort($bid, SORT_ASC, $prio, SORT_ASC, $sameRand, SORT_ASC, $data);
?>

Answer 7

put elements to be shuffled into an array and remove them from the initial array until the initial array is empty.
call shuffle on the created array
put the shuffled array into a new array with the results.