Group and count identical rows in a 2d array

Question

I am trying the group display values in a php array with how many times was duplicated in it.

Example:

[
    [6],
    [6],
    [6],
    [5,1],
    [3,3],
    [3,3],
    [3,2,1]
]

What I need as a result is the group of array and the count of them like this:

[[6],3],
[[5,1],1],
[[3,3],2],
[[3,2,1],1],

any type ?

EDIT

I tried to do it with this statement:

$result = array();
foreach ($myarray as $element) {
    $result[$element[0]][] = $element;
}

but I get the result as this:

{"6":[[6],[6],[6]],"5":[[5,1]],"3":[[3,3],[3,3],[3,2,1]]}

The problem is on the 3 group, I need to group [3,3] and [3,2,1] separately.

Answer 1

This seems to to do what you have asked.

<?php
    //This is your array of elements
    $array = [[6],[6],[6],[5,1],[3,3],[3,3],[3,2,1]];

    //This is a list of items that the program knows about, and their position
    $known_items = array();

    //For all the elements
    foreach($array as $item){
        //Sort the array to be in ascending order so that any combination will work
        asort($item);

        //We only want the item array to have values, and not keys
        $item = array_values( $item );

        //Make the content of this item a string so we can use it as a key in arrays
        $arrString = json_encode( $item );

        //Have we seen this item before?
        if( array_key_exists( $arrString , $known_items ) ){
            //Yes we have, increase the count
            $known_items[ $arrString ][1]++;
        } else {
            //No we haven't. Add it and start the count as 1
            $known_items[ $arrString ] = [ $item, 1 ];
        }

    }

    echo json_encode( array_values( $known_items), JSON_PRETTY_PRINT);