Explode array's data and make new array - php

Question

I have this array:
Array
(
[0] => Array
(
[0] => 1
[1] => a,b,c
)
[1] => Array
(
[0] => 5
[1] => d,e,f
)
)
I want the final array to be this:
Array
(
[0] => Array
(
[0] => 1
[1] => a
)
[1] => Array
(
[0] => 1
[1] => b
)
[2] => Array
(
[0] => 1
[1] => c
)
[3] => Array
(
[0] => 5
[1] => d
)
[4] => Array
(
[0] => 5
[1] => e
)
[5] => Array
(
[0] => 5
[1] => f
)
)
This is what I did:
<?php
$array = array(array(1,"a,b,c"),array(5,"d,e,f"));
$temp=array();
$count = 0;
foreach($array as $arr){
$rows = explode(",",$arr[1]);
foreach($rows as $row){
$temp[$count] = $arr;
$temp[$count][1] = $row;
$count++;
}
}
print_r($temp);
?>
This totally works but I was wondering if there was a better way to do this. This can be very slow when I have huge data.

Answer 1

Try like this way...
<?php
$array = array(array(1,"a,b,c"),array(5,"d,e,f"));
$temp=array();
$count = 0;
foreach($array as $arr){
$rows = explode(",",$arr[1]);
foreach($rows as $row){
$temp[$count][] = $arr[0];
$temp[$count][] = $row;
$count++;
}
}
/*print "<pre>";
print_r($temp);
print "<pre>";*/
?>

Answer 2

Here's a functional approach:
$result = array_merge(...array_map(function(array $a) {
return array_map(function($x) use ($a) {
return [$a[0], $x];
}, explode(",", $a[1]));
}, $array));
Try it online.
Or simply with two loops:
$result = [];
foreach ($array as $a) {
foreach (explode(",", $a[1]) as $x) {
$result[] = [$a[0], $x];
}
}
Try it online.
Timing these reveals that a simple loop construct is ~8 times faster.
functional: 4.06s user 0.08s system 99% cpu 4.160 total
loop: 0.53s user 0.05s system 102% cpu 0.561 total

Answer 3

If you need other way around,
$array = array(array(1, "a,b,c"), array(5, "d,e,f"));
$temp = [];
array_walk($array, function ($item, $key) use (&$temp) {
$second = explode(',', $item[1]);
foreach ($second as $v) {
$temp[] = [$item[0], $v];
}
});
print_r($temp);
array_walk — Apply a user supplied function to every member of an array
Here is working demo.