Group array values by trailing letters

Question

I have an array like so (generated from an API):

    [18] => 3107SkincareL
    [19] => 3INAL
    [20] => 3M
    [21] => 3rdRockEssentialsFL
    [22] => 4BeautyGroupL
    [23] => 4EVERMAGICCOSMETICSL

As you can see, some of the entries feature a trailing "L" or "FL". I would like to sort everything ending with "L" into a group and everything that ends with "FL" into a group and everything else in another group.

Answer 1

This should be what you are looking for:

<?php
$input = [
  18 => "3107SkincareL", 
  19 => "3INAL", 
  20 => "3M", 
  21 => "3rdRockEssentialsFL", 
  22 => "4BeautyGroupL", 
  23 => "4EVERMAGICCOSMETICSL", 
];
$output = [];
array_walk($input, function($entry) use (&$output) {
    if ("FL" == substr($entry, -2)) {
        $output["FL"][] = $entry;
    } else if ("L" == substr($entry, -1)) {
        $output["L"][] = $entry;
    } else {
        $output["?"][] = $entry;        
    }
});
print_r($output);

The output obviously is:

Array
(
    [L] => Array
        (
            [0] => 3107SkincareL
            [1] => 3INAL
            [2] => 4BeautyGroupL
            [3] => 4EVERMAGICCOSMETICSL
        )
    [FL] => Array
        (
            [0] => 3rdRockEssentialsFL
        )
    [?] => Array
        (
            [0] => 3M
        )
)