sorting 2d array with individual comparator using phps array_multisort

Question

I got a 2d-array containing a "column" on which this whole array is to be sorted. As I learned here, it is quite straightforward using array_multisort. My problem is, that this to be sorted over column contains values that needs to be compared in an unusual way. So I thought of something like this:

function main(){
    $toBeSorted = array(array(...), ..., array(...));
    $sortColumnIndex = n;
    $sort_column = array();

    //Code copied from provided link
    foreach ($toBeSorted as $row)
        $sort_column []= $row[$sortColumnIndex];

    array_multisort($this->comparator(),$sort_column, $toBeSorted);
}

function comparator(a,b){
    return 1;
}

As you can see, I want to pass my comparator to that sort-function. I probably think to much in a non-php way.

lortabac · Accepted Answer · 2012-09-06 11:02:51Z

0

There is the usort function, which sorts by using a callback.

Otherwise you could have a look at the array_walk and array_walk_recursive functions, which iterate over an array and apply a function to every member.

answered Sep 6, 2012 at 11:02

lortabac

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2 Comments

Milla Well Over a year ago

is there another function that works like usort but returns an array of positions of the elements? Just like pythons numpy.argsort? Because otherwise I cannot keep track of the other columns to sort the 2d-arrays?

lortabac Over a year ago

I don't think it exists. This is the list of all array sorting functions in PHP.

Milla Well · Accepted Answer · 2012-09-07 07:20:32Z

0

I solved it by transforming my sorting space in one, that array_multisort can handle:

...

$sortColumn = array();
foreach($toBeSorted as $value){
     $sortColumn[] = $this->transform($value);
}
array_multisort($sortColumn, $toBeSorted);

...

my transformation function simply does everything I imagined the callback would do.

function transform($value){
    //i.e. return real part of complex number
    //or parse strings or any kind of strange datatypes
}

answered Sep 7, 2012 at 7:20

Milla Well

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