Converting a string with comma separated value in a tree in PHP - php

Question

I have a csv file that contains a field with a category tree in a comma separated format like this:
MotherCategory, ChildCategory1, ChildCategory2, ecc.
Some records contains only a category, other ones two, other ones three or more.
I would like to be able to store in my db all the unique categories and organise every record with a parentid scheme where the parentid value is the id of the category one level up.
At the end I should have something like:
id: 1, catname: MotherCategory, parentid: NULL
id: 2, catname: ChildCategory1, parentid: 1
id: 3, catname: ChildCategory2, parentid: 2
I've already filtered the data removing duplicates with array_unique(), next using explode() I am able to separate the values and I was counting the values and separating the groups basing on the length of the resultant arrays to build a tree, but I think that at the moment I am missing something to get my final result.
I've the following code. Can someone please give me a hint to solve the problem?
$cats = array_of_comma_separated_values;
foreach ($cats as $cat) {
$catarray[] = explode(",",$cat);
}
//first level
$level1 = array_filter ($catarray, function($item) {
if (count($item) == 1) { return true; } return false;
});
//second level
$level2 = array_filter ($catarray, function($item) {
if (count($item) == 2) { return true; } return false;
});
$level3 = array_filter ($catarray, function($item) {
if (count($item) == 3) { return true; } return false;
});
$level4 = array_filter ($catarray, function($item) {
if (count($item) == 4) { return true; } return false;
});
$level5 = array_filter ($catarray, function($item) {
if (count($item) == 5) { return true; } return false;
});
$level6 = array_filter ($catarray, function($item) {
if (count($item) == 6) { return true; } return false;
});
$level7 = array_filter ($catarray, function($item) {
if (count($item) == 7) { return true; } return false;
});
This gives me several arrays that i've to iterate to achieve what i'm looking for.
Now thanks to the suggestion from Kovlar I'm working on something based on array_pop() and array_replace_recurive().
I've edited the post because maybe I was not so clear.

Answer 1

I suggest the use of array_replace_recursive() to simplify the tree-merging :)
// $tree will contain the tree at the end of the script
$tree = [];
// we treat each row of the csv one by one
foreach($csv_rows as $row) {
// first, we split the string into an array
$root_to_leaf = explode(',', $row['root_to_leaf']);
// this is the "leaf" we want to append to the tree
$leaf = [array_pop($root_to_leaf) => $row['value']];
// we rebuild the path from the leaf to the root
while(!empty($root_to_leaf)) {
// add the next branching toward the root
$leaf = [array_pop($root_to_leaf) => $leaf];
}
// we append the leaf to the tree
$tree = array_replace_recursive($tree, $leaf);
}