PHP Multidimensional Array: Combine By Key And Add Values Of Another Key - php

Question

have an array like this:
array (
'#attributes' =>
array (
'status' => 'ok',
),
'time_entries' =>
array (
'#attributes' =>
array (
'page' => '1',
'per_page' => '100',
'pages' => '1',
'total' => '33',
),
'time_entry' =>
array (
0 =>
array (
'time_entry_id' => '1411884',
'staff_id' => '22384',
'project_id' => '11116',
'task_id' => '3296',
'hours' => '1.75',
'date' => '2017-02-20',
'notes' => 'What is Quadra, Events Slider, Event Page Setup',
'billed' => '0',
),
1 =>
array (
'time_entry_id' => '1411254',
'staff_id' => '22384',
'project_id' => '11116',
'task_id' => '3296',
'hours' => '1.5',
'date' => '2017-02-17',
'notes' => 'Events Slider, Background overlay, Intro',
'billed' => '0',
),
2 =>
array (
'time_entry_id' => '1410694',
'staff_id' => '22384',
'project_id' => '11116',
'task_id' => '3296',
'hours' => '2.75',
'date' => '2017-02-16',
'notes' => 'Background Image SVGs, Header, Footer',
'billed' => '0',
),
3 =>
array (
'time_entry_id' => '1410586',
'staff_id' => '22384',
'project_id' => '11116',
'task_id' => '3296',
'hours' => '0.5',
'date' => '2017-02-15',
'notes' => 'Site Background
Assign Less Variables',
'billed' => '0',
),
4 =>
array (
'time_entry_id' => '1409621',
'staff_id' => '22384',
'project_id' => '11116',
'task_id' => '3296',
'hours' => '0.25',
'date' => '2017-02-14',
'notes' => 'Theme Install',
'billed' => '0',
),
...it actually goes on further than those first 4. What I am looking to do is sort these arrays by the key ["task_id"] so that I can group those together, and then add together the ["hours"] key - so that at the end I can output the total number of hours worked on under each task_id.
I've tried a bit of 'array_merge_recursive'and similar but I'm at a loss; this is PHP a good bit above my level. Help very appreciated.

Answer 1

So you're probably just better off doing a group by and summation by generating a new set of data rather than trying to modify this array.
Something like this will give you what you're looking for:
$time_entries = $your_array["time_entries"]["time_entry"];
$task_hours = [];
foreach ($time_entries as $time_entry) {
if (!isset($task_hours[$time_entry["task_id"]])) {
$task_hours[$time_entry["task_id"]] = 0;
}
$task_hours[$time_entry["task_id"]] += (float) $time_entry["hours"];
}
$task_hours would give you a value like:
Array
(
[3296] => 5
[1879] => 0.25
)

Answer 2

Instead of sorting the array and then summing the hours why not process over the relevant part of that array and do the summation all in one go.
$tots = array();
foreach( $array['time_entry'] as $task ) {
if ( isset($tots['task_id']) ) {
$tots['task_id'] += $task['hours'];
} else {
$tots['task_id'] = $task['hours'];
}
}
You should now have an array where the key is the task_id and its value is the summation of all that keys hours.
If you want the task_id's in order then sort the $tots array before outputing any results
ksort($tots);
If you want the results in order of the number of hours
asort($tots);