How can I convert PHP array to accociative array [closed] - php

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I want to convert this array based on array value.
Before underscore value is convert to key and after '_" value is convert to value
Original array
Array (
[0] => 1_1
[1] => 1_2
[2] => 1_3
[3] => 1_4
[4] => 1_5
[5] => 1_6
[6] => 3_1
[7] => 3_2
[8] => 3_4
[9] => 3_5
[10] => 4_1
[11] => 4_2
[12] => 4_3
)
I want to convert it to :
Array(
[1]=> array(
[0]=>1,
[1]=>2,
[2]=>3,
[3]=>4,
[4]=>5,
[5]=>6
),
[3]=> array(
[0]=>1,
[1]=>2,
[2]=>4,
[3]=>5,
[4]=>5
),
[4]=> array(
[0]=>1,
[1]=>2,
[2]=>3
)
);

Answer 1

This should do the job :
$array = Array (
0 => "1_1",
1 => "1_2",
2 => "1_3",
3 => "1_4",
4 => "1_5",
5 => "1_6",
6 => "3_1",
7 => "3_2",
8 => "3_4",
9 => "3_5",
10 => "4_1",
11 => "4_2",
12 => "4_3"
);
// Create a new empty array
$result = array();
// Loop throught your first array
foreach ($array as $data) {
// Foreach data, you explode by '_'so you will get an array
// Eg. $new_data = array(0 => '1', 1 => '1') for $data = "1_1"
$new_data = explode('_', $data);
// Now you just have to add the data as you want
$result[$new_data[0]][] = $new_data[1];
}
var_dump($result);
The output is :
array (size=3)
1 =>
array (size=6)
0 => string '1' (length=1)
1 => string '2' (length=1)
2 => string '3' (length=1)
3 => string '4' (length=1)
4 => string '5' (length=1)
5 => string '6' (length=1)
3 =>
array (size=4)
0 => string '1' (length=1)
1 => string '2' (length=1)
2 => string '4' (length=1)
3 => string '5' (length=1)
4 =>
array (size=3)
0 => string '1' (length=1)
1 => string '2' (length=1)
2 => string '3' (length=1)

Answer 2

This should work:
$resp = [];
foreach ($arr as $a) {
$values = explode('_', $a);
$resp[$values[0]][] = $values[1];
}
For the reverse:
$resp = [];
foreach ($resp as $key => $arr) {
foreach ($arr as $a) {
$resp[] = $key . '_' . $a;
}
}