PHP grouping arrays within array by value - php

Question

Hi I've got a bit of a problem and I can't seem to find the answer. I have an array with arrays in it and want to group these sub arrays into groups based on the same value for a field. This is my code and allows me to sort my arrays based on the arrays inside values. How do I group the result based on shared values? I probably won't know all the values as some are based on date and I want to for instance group all per day/month
if($filter == "ORDER BY TODO_REF DESC"){
$type_sort = 0;
};
if($filter == "ORDER BY TODO_PRIO DESC"){
$type_sort = 2;
};
if($filter == "ORDER BY TODO_DEAD DESC"){
$type_sort = 3;
};
function aasort (&$array, $key) {
$sorter=array();
$ret=array();
reset($array);
foreach ($array as $ii => $va) {
$sorter[$ii]=$va[$key];
}
asort($sorter);
foreach ($sorter as $ii => $va) {
$ret[$ii]=$array[$ii];
}
$array=$ret;
}
aasort($test_array, $type_sort);
print_r($test_array);
Current output:
priority
Array
(
[3] => Array
(
[0] => 2
[1] => sdfsdgdfgdfgdfg
[2] => 3
[3] => 2013-05-30 13:53:23
)
[2] => Array
(
[0] => 1
[1] => This must also be done
[2] => 4
[3] => 2013-03-28 12:13:34
)
[1] => Array
(
[0] => 1
[1] => testing this show me 2
[2] => 5
[3] => 2029-02-23 17:27:20
)
[0] => Array
(
[0] => 1
[1] => Do this task and make sure it gets done
[2] => 5
[3] => 2013-06-28 12:12:41
)
)
What I want would be something like this, where they are split into seperate arrays based on sub array key 2:
Array
(
[3] => Array
(
[0] => 2
[1] => sdfsdgdfgdfgdfg
[2] => 3
[3] => 2013-05-30 13:53:23
)
)
Array
(
[2] => Array
(
[0] => 1
[1] => This must also be done
[2] => 4
[3] => 2013-03-28 12:13:34
)
)
Array
(
[1] => Array
(
[0] => 1
[1] => testing this show me 2
[2] => 5
[3] => 2029-02-23 17:27:20
)
[0] => Array
(
[0] => 1
[1] => Do this task and make sure it gets done
[2] => 5
[3] => 2013-06-28 12:12:41
)
)

Answer 1

$array_1 = array();
$array_2 = array();
foreach($test_array as $item) {
if($item[0] == 1) {
$array_1[] = $item;
} elseif($item[0] == 2) {
$array_2[] = $item;
}
}
$final_array = array($array_1, $array_2);
There must be more optimized codes, but this should serve your needs.

Answer 2

array_multisort() is what you're after it will allow you to sort primary array by sub array and maintain the key value link
I use the below for sorting a rather hefty multi-dimensional array based off sort order arrows asc/desc on a table with many columns and sortable columns. Its abit of a mess but you should be able to follow it.
if (strlen($_GET['col'])<1) {
foreach ($dataarray as $key => $row) {
$spend[$key] = $row[6];
}
array_multisort($spend, SORT_DESC, $dataarray);
} else if ($_GET['col']=="spend"){
foreach ($dataarray as $key => $row) {
$spend[$key] = $row[3];
}
if ($_GET['order']=="asc") {
array_multisort($spend, SORT_ASC, $dataarray);
} else {
array_multisort($spend, SORT_DESC, $dataarray);
}
} else if ($_GET['col']=="name"){
foreach ($dataarray as $key => $row) {
$name[$key] = $row[1];
}
if ($_GET['order']=="asc") {
array_multisort($name, SORT_ASC, $dataarray);
} else {
array_multisort($name, SORT_DESC, $dataarray);
}
} else if ($_GET['col']=="avg"){
foreach ($dataarray as $key => $row) {
$avg[$key] = $row[4];
}
if ($_GET['order']=="asc") {
array_multisort($avg, SORT_ASC, $dataarray);
} else {
array_multisort($avg, SORT_DESC, $dataarray);
}
} else if ($_GET['col']=="sites"){
foreach ($dataarray as $key => $row) {
$sites[$key] = $row[5];
}
if ($_GET['order']=="asc") {
array_multisort($sites, SORT_ASC, $dataarray);
} else {
array_multisort($sites, SORT_DESC, $dataarray);
}
} else if ($_GET['col']=="rate"){
foreach ($dataarray as $key => $row) {
$rate[$key] = $row[6];
}
if ($_GET['order']=="asc") {
array_multisort($rate, SORT_ASC, $dataarray);
} else {
array_multisort($rate, SORT_DESC, $dataarray);
}
} else {
foreach ($dataarray as $key => $row) {
$spend[$key] = $row[2];
}
array_multisort($spend, SORT_DESC, $dataarray);
}

Answer 3

Rather than a block of if-elseif-elseif-elseif...else conditions to determine the sorting/grouping column, I always recommend a lookup array followed by a very quick isset() call. I find this syntax to be more succinct, more readable, and easier to maintain.
So that grouped data is sorted properly, sort the data ahead of time (while it is still in its simpler form). usort() with the spaceship operator (php7) will do all of the hardwork for you. Just be sure to pass the $groupsort variable into the function scope with use.
As you iterate the input array, isolate the identifying column value (and prepare it as necessary), then use it as a temporary key to determine the group in which the $row data should be stored.
Finally, use array_values() to remove the temporary identifying keys (if desired).
Code: (Demo)
$filter = "ORDER BY TODO_PRIO DESC";
$lookup = [
"ORDER BY TODO_REF DESC" => 0,
"ORDER BY TODO_PRIO DESC" => 2,
"ORDER BY TODO_DEAD DESC" => 3
];
$groupsort = isset($lookup[$filter]) ? $lookup[$filter] : 0;
$array = [
[1, "Do this task and make sure it gets done", 5, "2013-06-28 12:12:41"],
[1, "testing this show me 2", 5, "2029-02-23 17:27:20"],
[1, "This must also be done", 4, "2013-03-28 12:13:34"],
[2, "sdfsdgdfgdfgdfg", 3, "2013-05-30 13:53:23"],
[2, "Another priority", 3, "2013-03-28 11:11:11"]
];
// sort DESC on $groupsort column values
usort($array, function($a, $b)use($groupsort) { return $b[$groupsort] <=> $a[$groupsort]; });
// group by $groupsort column values
foreach ($array as $row) {
$id = $row[$groupsort]; // just to improve readability
if ($groupsort == 3) { $id = substr($id, 0, 10); } // remove time from datetime stamp
$result[$id][] = $row; // store the current value
}
var_export(array_values($result)); // reindex first level (remove temp keys);
Output:
array (
0 =>
array (
0 =>
array (
0 => 1,
1 => 'Do this task and make sure it gets done',
2 => 5,
3 => '2013-06-28 12:12:41',
),
1 =>
array (
0 => 1,
1 => 'testing this show me 2',
2 => 5,
3 => '2029-02-23 17:27:20',
),
),
1 =>
array (
0 =>
array (
0 => 1,
1 => 'This must also be done',
2 => 4,
3 => '2013-03-28 12:13:34',
),
),
2 =>
array (
0 =>
array (
0 => 2,
1 => 'sdfsdgdfgdfgdfg',
2 => 3,
3 => '2013-05-30 13:53:23',
),
1 =>
array (
0 => 2,
1 => 'Another priority',
2 => 3,
3 => '2013-03-28 11:11:11',
),
),
)