reorder multi-dimensional array in PHP - php

Question

I have a multi-dimensional array that I need to reorder.
I need to sort the array so that the first thing that will take into account the LEVEL, then SECTION, where SECTION is equal to the ID of the previous element.
Can someone help me?
Thanks.
Here is the array:
Array
(
[0] => Array
(
[LEVEL] => 1
[ID] => 1_1
[SECTION] => _
)
[1] => Array
(
[LEVEL] => 1
[ID] => 1_2
[SECTION] => _
)
[2] => Array
(
[LEVEL] => 2
[ID] => 2_1
[SECTION] => 1_1
)
[3] => Array
(
[LEVEL] => 2
[ID] => 2_2
[SECTION] => 1_2
)
[4] => Array
(
[LEVEL] => 3
[ID] => 3_1
[SECTION] => 2_1
)
[5] => Array
(
[LEVEL] => 3
[ID] => 3_2
[SECTION] => 2_2
)
and here is the result I need:
Array
(
[0] => Array
(
[LEVEL] => 1
[ID] => 1_1
[SECTION] => _
)
[2] => Array
(
[LEVEL] => 2
[ID] => 2_1
[SECTION] => 1_1
)
[4] => Array
(
[LEVEL] => 3
[ID] => 3_1
[SECTION] => 2_1
)
[1] => Array
(
[LEVEL] => 1
[ID] => 1_2
[SECTION] => _
)
[3] => Array
(
[LEVEL] => 2
[ID] => 2_2
[SECTION] => 1_2
)
[5] => Array
(
[LEVEL] => 3
[ID] => 3_2
[SECTION] => 2_2
)

Answer 1

Correct me if I'm wrong, but it looks like all the information you need for sorting is in the ID. Groups are contained in the number following the underscore, and levels in the number preceding it. Therefore, the order can be determined by reversing the order of these numbers and performing a natural order string comparison:
1_1, 2_1, 3_1, 4_1, 1_2, 2_2, 3_2, 1_3, 2_3, 3_3, 4_3, etc.
Becomes:
1-1, 1-2, 1-3, 1-4, 2-1, 2-2, 2-3, 3-1, 3-2, 3-3, 3-4, etc.
Therefore, if your initial array is called $arr:
$ord = array_map(function($a) {return $a['ID'];}, $arr);
$ord = preg_replace('/(\d+)_(\d+)/', '$2-$1', $ord);
array_multisort($ord, SORT_NATURAL, $arr);
If you're using PHP 5.5:
$ord = preg_replace('/(\d+)_(\d+)/', '$2-$1', array_column($arr, 'ID'));
array_multisort($ord, SORT_NATURAL, $arr);

Answer 2

It was interesting to work on your question, Please check my below solution on your query,
It's working fine for me:
$arrData=array(
array(
'LEVEL'=>1,
'ID'=>'1_1',
'SECTION'=>''
),
array(
'LEVEL'=>'3',
'ID'=>'3_1',
'SECTION'=>''
),
array(
'LEVEL'=>'3',
'ID'=>'3_2',
'SECTION'=>''
),
array(
'LEVEL'=>2,
'ID'=>'2_1',
'SECTION'=>''
),
array(
'LEVEL'=>1,
'ID'=>'1_2',
'SECTION'=>''
),
);
$arrLevels=array();
foreach($arrData as $key=>$val)
{
if(!in_array($val['LEVEL'], $arrLevels))
{
$arrLevels[]=$val['LEVEL'];
}
}
sort($arrLevels);
$arrDataNew=array();
$arrSortIndexes=array();
do
{
foreach ($arrLevels as $level)
{
//array_walk($arrData, 'sort_data',$level,$arrSortIndexes,$arrData);
$arrCurrentLevel=array();
foreach($arrData as $key=>$dataC)
{
if($dataC['LEVEL']==$level)
{
$arrCurrentLevel[intval(end(explode('_',$dataC['ID'])))]=$key;
}
}
if(sizeof($arrCurrentLevel)>0)
{
$keyOfArrData=$arrCurrentLevel[min(array_keys($arrCurrentLevel))];
$arrDataNew[]=$arrData[$keyOfArrData];
unset($arrData[$keyOfArrData]);
}
}
}while(sizeof($arrData)>0);
print_r($arrDataNew);

Answer 3

I finally solved this way, it is not the fastest solution, but it works at least as need
$i=0;
foreach ($polozky as $id => $polozka)
{
if ($polozka["LEVEL"] == 1)
{
$i++;
}
}
$j=0;
foreach ($polozky as $id => $polozka)
{
if ($polozka["LEVEL"] == 2)
{
$j++;
}
}
$k=0;
foreach ($polozky as $id => $polozka)
{
if ($polozka["LEVEL"] == 3)
{
$k++;
}
}
$stack = array();
for($l = 0; $l < $i; ++$l)
{
array_push($stack, $polozky[$l]);
$id1 = $polozky[$l]["ID"];
for($m = 0; $m < $j+$i; ++$m)
{
if($polozky[$m]["SECTION"] == $id1)
{
array_push($stack, $polozky[$m]);
$id2 = $polozky[$m]["ID"];
for($n = 0; $n < $k+$j+$i; ++$n)
{
if($polozky[$n]["SECTION"] == $id2)
{
array_push($stack, $polozky[$n]);
}
}
}
}
}