More efficient way of merging two arrays - php

Question

I am comparing each element of array with every other element of array and if two elements have the same source/target, target/source I merge the inner array with employees e.g.
0=> source - 3 target - 4 officers => 0 - 'Aberdeen Asset Management PLC'
1=> source - 3 target - 4 officers => 0 - 'whatever'
it would be merged to
0=> source - 3 target - 4 officers => 0 - 'Aberdeen Asset Management PLC', 1 - 'whatever'
Here is how the data looks like:
My code is really inefficient with 1000 on more rows to go through the execution takes about 90 seconds which is unacceptable for this sort of thing.
foreach ($edges as $i => &$edge) {
for ($j = $i + 1; $j < count($edges); $j++) {
if ($edge['source'] == $edges[$j]['source'] && $edge['target'] == $edges[$j]['target']) {
foreach ($edges[$j]['officers'] as $officer) {
array_push($edge['officers'], $officer);
}
array_splice($edges, $j, 1);
}
}
}

Answer 1

The solution using array_search, array_keys, array_slice and array_merge functions:
// an exemplary array
$edges = [
0 => ['source' => 3, 'target' => 4, 'officers' => ['Aberdeen Asset Management PLC']],
1 => ['source' => 3, 'target' => 4, 'officers' => ['whatever']],
3 => ['source' => 4, 'target' => 7, 'officers' => ['Jason']],
4 => ['source' => 4, 'target' => 5, 'officers' => ['John']],
5 => ['source' => 4, 'target' => 7, 'officers' => ['Bourne']]
];
foreach ($edges as $k => &$v) {
$next_slice = array_slice($edges, array_search($k, array_keys($edges)) + 1);
foreach ($next_slice as $key => $item) {
if ($item['source'] == $v['source'] && $item['target'] == $v['target']) {
$v['officers'] = array_merge($v['officers'], $item['officers']);
unset($edges[$k + $key + 1]);
}
}
}
print_r($edges);
DEMO link

Answer 2

I think you should do this (updated):
// we will have new array with officers
$new_items = array();
foreach ($edges as $edge) {
// create unique keys for `source-target` and `target-source` pairs
$source_target = $edge['source'] . ':' . $edge['target'];
$target_source = $edge['target'] . ':' . $edge['source'];
// check if unique keys exists in `new_items`
if (!isset($new_items[$source_target]) && !isset($new_items[$target_source])) {
// if unique key doesn't exist - create a new one
$new_items[$source_target] = $edge;
} elseif (isset($new_items[$source_target])) {
// if unique key exists `$source_target` - add an officer to it
$new_items[$source_target]['officers'][] = $edge['officers'][0];
} else {
// if unique key exists `$target_source` - add an officer to it
$new_items[$target_source]['officers'][] = $edge['officers'][0];
}
}
// for returning to numeric indexes use `array_values`
$new_items = array_values($new_items);