Get previous and next array by key from array object - php

Question

i have array object and want get 2 previous and and 2 next array group by specific key.
Array
(
[467] => stdClass Object
(
[id] => 467
[user_id] => 1
)
[468] => stdClass Object
(
[id] => 468
[user_id] => 1
)
[469] => stdClass Object
(
[id] => 469
[user_id] => 1
)
[474] => stdClass Object
(
[id] => 474
[user_id] => 1
)
[475] => stdClass Object
(
[id] => 475
[user_id] => 1
)
[479] => stdClass Object
(
[id] => 479
[user_id] => 1
)
[480] => stdClass Object
(
[id] => 480
[user_id] => 1
)
)
If key define 474 will result:
Previous array group from key 469 and 468
Next array group from key 475 and 479
If don't have previous and next array, i want no result
I try this method, but not working.
$val = 474;
$currentKey = array_search($val, $array);
$before = (isset($array[$currentKey - 2])) ? $array[$currentKey - 2] :
$after = (isset($array[$currentKey + 2])) ? $array[$currentKey + 2] : $array[0];
var_dump($before, $after);
Please help.

Answer 1

What my method will do is, search for the $key value and return its offset in the array. You were using array_search() on the input array's values, so that's where it fell flat.
Then if the offset value is not false, I attempts to slice the 5 desired subarrays from the input array. If it doesn't return 5, then it fails.
The second code will not trigger a failure if the collection of subarrays is less than 5.
Code: (Demo)
$array=[
467=>(object)['id'=>467,'user_id'=>1],
468=>(object)['id'=>468,'user_id'=>1],
469=>(object)['id'=>469,'user_id'=>1],
474=>(object)['id'=>474,'user_id'=>1],
475=>(object)['id'=>475,'user_id'=>1],
479=>(object)['id'=>479,'user_id'=>1],
480=>(object)['id'=>480,'user_id'=>1]
];
$key=480;
// require 5 subarrays or none:
if(($offset=array_search($key,array_keys($array)))<2 || sizeof($result=array_slice($array,$offset-2,5))!=5){
echo "Fail";
}else{
var_export($result);
}
echo "\n---\n";
// allow any number of subarrays up to 5:
if(($offset=array_search($key,array_keys($array)))===false){
echo "Fail";
}else{
// adjust $offset and $length values to handle array "overflow"
if($offset<2){
$length=$offset+3;
}elseif(($diff=sizeof($array)-$offset)<3){
$length=$diff+2;
}else{
$length=5;
}
$offset=max(0,$offset-2);
var_export(array_slice($array,$offset,$length));
}
Output:
Fail
---
array (
0 =>
stdClass::__set_state(array(
'id' => 475,
'user_id' => 1,
)),
1 =>
stdClass::__set_state(array(
'id' => 479,
'user_id' => 1,
)),
2 =>
stdClass::__set_state(array(
'id' => 480,
'user_id' => 1,
)),
)
Here is a visual representation and some more explanation of what the second method is doing:
The following explanation uses a 6-element array to demonstrate the calculations.
I = 'elements labeled by their indices'
S = 'the slice'
T = 'target index'
L = 'length of slice'
I ST ST ST ST ST ST When $target index is:
0 ╗0 ╗ ╗ 0, then $offset=0 and $length=3
1 ║ ║1 ║ ╗ 1, then $offset=0 and $length=4
2 ╝ ║ ║2 ║ ╗ 2, then $offset=0 and $length=5
3 ╝ ║ ║3 ║ ╗ 3, then $offset=1 and $length=5
4 ╝ ║ ║4 ║ 4, then $offset=2 and $length=4
5 ╝ ╝ ╝5 5, then $offset=3 and $length=3
L: 3 4 5 5 4 3

Answer 2

Since your array is not in the sequence, try this one Demo.
$arr = array( 467 => (object) ['id' => 467, 'user_id' => 1],
468 => (object) ['id' => 468, 'user_id' => 1],
469 => (object) ['id' => 469, 'user_id' => 1],
474 => (object) ['id' => 474, 'user_id' => 1],
475 => (object) ['id' => 475, 'user_id' => 1],
479 => (object) ['id' => 479, 'user_id' => 1],
480 => (object) ['id' => 480, 'user_id' => 1],);
$find = 474;
$before2 = $before1 = $next1 = $next2 = array();
$flag = false;
foreach ($arr as $key => $val) {
if($key == $find) {
$flag = true;
}
if(!$flag) {
if(!empty($before1)){
$before2 = $before1;
}
$before1 = $val;
}
if($key != $find) {
if($flag && empty($next2)){
if(!empty($next1)){
$next2 = $next1;
}
$next1 = $val;
}
if(!empty($next2)){
break;
}
}
}
if($flag) {
echo "matching values =>";
var_dump($before2);
var_dump($before1);
var_dump($next1);
var_dump($next2);
} else {
echo "given index not found!";
}