How to merge selected elements of an array in PHP? - php

Question

I have an array as
$array = array (
0 => array( 'name' => 'zero'),
1 => array( 'name' => 'one'),
2 => array( 'name' => 'two'),
3 => array( 'name' => 'three'),
4 => array( 'name' => 'four'),
5 => array( 'name' => 'five'),
6 => array( 'name' => 'six'),
);
and I need to merge some elements according to a pattern
$pattern = array(
array('from'=>1, 'to'=>2, 'note'=>'something'),
array('from'=>3, 'to'=>5, 'note'=>'something'),
array('from'=>6, 'to'=>6, 'note'=>'something'),
);
How can I merge the elements to get an array of
$ result = array(
['0'] => array('name'=>'zero'),
['1,2'] => array('name'=>'one+two', 'note'=>'something'),
['3,4,5'] => array('name'=>'three+four+five', 'note'=>'something'),
['6'] => array('name'=>'six', 'note'=>'something'),
);
I understand that I should iterate one array in a loop and check the other one for the corresponding element to create a new array, but which one should I iterate?

Answer 1

If the array keys aren’t actually important, then I’d go about it like this:
$result = $processed = [];
foreach($pattern as $p) { // loop over the patterns
$temp = [];
for($i = $p['from']; $i <= $p['to']; ++$i) { // loop over from -> to
$temp[] = $array[$i]['name']; // collect names of those items
$processed[] = $i; // store index of item as an already processed one
}
$result[] = ['name' => implode('+', $temp), 'note' => $p['note']];
}
$temp = [];
foreach($array as $key => $item) {
if(!in_array($key, $processed)) { // if index is not in list of already processed items
$temp[] = $item['name'];
}
}
array_unshift($result, ['name' => implode('+', $temp)]); // add to front of result
That will get you a result of the form
Array
(
[0] => Array
(
[name] => zero
)
[1] => Array
(
[name] => one+two
[note] => something
)
[2] => Array
(
[name] => three+four+five
[note] => something
)
[3] => Array
(
[name] => six
[note] => something
)
)