How can I extract values from a multidimensional array grouped by some value within it using PHP?
I have an array that looks like this: -
Array (
[0] => Array ( [id] => 10 [group] => 11 )
[1] => Array ( [id] => 11 [group] => 13 )
[2] => Array ( [id] => 12 [group] => 13 )
[3] => Array ( [id] => 13 [group] => 13 )
[4] => Array ( [id] => 14 [group] => 16 )
[5] => Array ( [id] => 15 [group] => 16 )
[6] => Array ( [id] => 16 [group] => 16 )
)
For each group in this array, I want to create an array that stores the IDs. In my example, I have 3 groups, so I want to get 3 arrays, for example:
Array ( [0] => 10)
Array ( [0] => 11
[1] => 12
[2] => 13)
Array ( [0] => 14
[1] => 15
[2] => 16)
Is this possible, how can I do this?
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This will help you get started. https://iconoun.com/demo/temp_icold.php
<?php // demo/temp_icold.php
/**
* Manipulate multi-dimensional arrays
*
* https://stackoverflow.com/questions/45422046/how-to-extract-values-from-multidimensional-array-grouped-by-some-value-inside-i
*/
error_reporting(E_ALL);
echo '<pre>';
$original = Array (
'0' => Array ( 'id' => 10, 'group' => 11 ),
'1' => Array ( 'id' => 11, 'group' => 13 ),
'2' => Array ( 'id' => 12, 'group' => 13 ),
'3' => Array ( 'id' => 13, 'group' => 13 ),
'4' => Array ( 'id' => 14, 'group' => 16 ),
'5' => Array ( 'id' => 15, 'group' => 16 ),
'6' => Array ( 'id' => 16, 'group' => 16 ),
);
print_r($original);
foreach ($original as $arr)
{
$ndx = 'group' . $arr['group'];
$out[$ndx][] = $arr['id'];
}
print_r($out);
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You can achieve this with different methods, but the simplest is probably the foreach () loop . In the example below, I go through $a
(your sample array) and create a new array named $grouped
with the index as the attribute value group
.
In my example, I am not duplicating the ID inside $group
. If you need duplicates, you can remove the second statement if
.
$a = [
['id' => 10, 'group' => 11],
['id' => 11, 'group' => 13],
['id' => 12, 'group' => 13],
['id' => 13, 'group' => 13],
['id' => 14, 'group' => 16],
['id' => 15, 'group' => 16],
['id' => 16, 'group' => 16],
];
$grouped = [];
foreach ($a as $entry) {
if (! array_key_exists($entry['group'], $grouped)) {
$grouped[$entry['group']] = [];
}
if (! in_array($entry['id'], $grouped[$entry['group']])) {
$grouped[$entry['group']][] = $entry['id'];
}
}
var_dump($grouped);
The example outputs the following:
array(3) {
[11]=>
array(1) {
[0]=>
int(10)
}
[13]=>
array(3) {
[0]=>
int(11)
[1]=>
int(12)
[2]=>
int(13)
}
[16]=>
array(3) {
[0]=>
int(14)
[1]=>
int(15)
[2]=>
int(16)
}
}
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$result_array = array();
foreach($array_name as $sub_array){
$result_array[$sub_array['group']][] = $sub_array['id'];
}
This will loop through your input array and create a 2D results array indexed with your group values. To extract a grouped result, just an index on the group itself:$result_array['GROUP_NUMBER'];
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Here's my example:
<?php
$arr = array(
array("id"=>10,"group"=>11),
array("id"=>11,"group"=>13),
array("id"=>12,"group"=>13),
array("id"=>13,"group"=>13),
array("id"=>14,"group"=>16),
array("id"=>15,"group"=>16),
array("id"=>16,"group"=>16)
);
echo "<pre>".print_r(groupsToArrays($arr),true)."</pre>";
function groupsToArrays($arr, $groupkey = "group") {
$main = array();
$group = 0;
$arr[] = array("id"=>"end", $groupkey => "0");
foreach($arr as $key => $value) {
if($group != $value[$groupkey]) {
if($key != 0) $main[$group] = $tempArray;
if($value['id'] == "end") continue;
$group = $value[$groupkey];
$tempArray = array();
}
$tempArray[] = $value;
}
return $main;
}
This function will loop through your array and check the key $groupkey
and add each match to its own array.
This is the return:
Array
(
[11] => Array
(
[0] => Array
(
[id] => 10
[group] => 11
)
)
[13] => Array
(
[0] => Array
(
[id] => 11
[group] => 13
)
[1] => Array
(
[id] => 12
[group] => 13
)
[2] => Array
(
[id] => 13
[group] => 13
)
)
[16] => Array
(
[0] => Array
(
[id] => 14
[group] => 16
)
[1] => Array
(
[id] => 15
[group] => 16
)
[2] => Array
(
[id] => 16
[group] => 16
)
)
)
So now you can access this array of groups by doing the following:
$groups = groupsToArrays($arr);
print_r($groups[$groupID]);
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