2d array - group by value and sum up same keys' values - php

Question

Hello and thanks for taking the time to look at my question.
My current problem is that, I have the following array ($topics_percentage):
Array
(
[0] => Array
(
[id] => 8989
[cat] => Category 1
[completed] => 0
)
[1] => Array
(
[id] => 8919
[cat] => Category 2
[completed] => 1
)
[2] => Array
(
[id] => 8913
[cat] => Category 2
[completed] => 1
)
[3] => Array
(
[id] => 8947
[cat] => Category 1
[completed] => 1
)
[4] => Array
(
[id] => 8949
[cat] => Category 3
[completed] => 1
)
)
What I need to get, is something like the following example:
Array
(
[Category 1] => Array
(
[noncompleted] => 1
[completed] => 1
)
[Category 2] => Array
(
[completed] => 2
)
[Category 3] => Array
(
[completed] => 1
)
)
What I've tried so far is this:
$class_array = [];
foreach ($topics_percentage as $v) {
$complete = $v['completed'];
$class_array[$v['cat']][] =
($complete == 0 ? 'noncompleted' : 'completed');
}
Which returns the following:
Array
(
[Category 1] => Array
(
[0] => noncompleted
[1] => completed
)
[Category 2] => Array
(
[0] => completed
[1] => completed
)
[Category 3] => Array
(
[0] => completed
)
)
I'm weak when it comes to arrays, and can't figure out the logic.
Thanks in advance.

Answer 1

Try this:
$values = array_unique(array_map(
function ($v) { return $v['cat']; },
$array
));
$result = array();
foreach ($values as $val) {
$flt = array_filter($array, function ($v) use ($val) {
return $v['cat'] == $val;
});
$cnt = count(array_filter($array, function ($v) use ($val) {
return $v['completed'];
}));
$result[$val] = array(
'completed' => $cnt,
'noncompleted' => count($flt) - $cnt
);
}

Answer 2

Try this:
foreach ($topics_percentage as $v) {
$complete = $v['completed'];
if ($complete == 1) {
$class_array[$v['cat']]['completed']++;
} else {
$class_array[$v['cat']]['uncompleted']++;
}
}
You should, of course, preinitialize the array before you count up values, but the basic idea is to use array cells as numeric values to be added or substracted from.