Question

I’ve two PHP Arrays. The first one contains a sort order. The second one contains the data which i need to sort. I have no idea how to solve it…

What I’m trying to get is a list, sorted by the values of the first array (order.txt). Any suggestions?

<li>Item [2]</li>
<li>Item [1]</li>
<li>Item [3]</li>

Order

Array
(
    [0] => 2
    [1] => 1
    [2] => 3
)

Data

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => 00134258.jpg
            [size] => 2787
        )

    [1] => Array
        (
            [id] => 2
            [name] => 80132454.jpg
            [size] => 2667
        )

    [2] => Array
        (
            [id] => 3
            [name] => 13134218.jpg
            [size] => 2787
        )

)

Here are the code which produces the arrays above:

<?php

    $order = file('order.txt');

    foreach ($order as $key => $value) {
        $order = json_decode($value, true);
    }

    print_r($order);


    $file = file('db.txt');

    foreach ($file as $key => $value) {
        $file_data[] = json_decode($value, true);
    }

    print_r($file_data);
?>

This are the json strings:

order.text

{"0":"2","1":"1","2":"3"}

db.txt

{"id":"1","name":"00134258.jpg","size":2787}
{"id":"2","name":"80132454.jpg","size":2667}
{"id":"3","name":"13134218.jpg","size":2787}

Answer 1

Make a new array where the keys are the id of the data, then loop through your order array and assign the values to an ordered array…

<?php
  // loop through the file data
  foreach($file_data as $v){
    // assign values to new array with the data id as it's key
    $identified[$v['id']] = $v;
  }
  // loop through the order array
  foreach($order as $v){
    // pull the data values from the identified array by their key
    $ordered[] = $identified[$v];
  }
  // check it has all worked out as planned ;)
  print_r($ordered);
?>

Alternatively… in line with @hakre’s method, first create array ordered by index, and then use array_multisort method.

<?php
  foreach($file_data as $v){
    $ordered[$v['id']] = $v;
  }
  array_multisort($order, $ordered);
  print_r($ordered);
?>