Question

I need to sort some data that is not coming from a database, but is structured like a sql result set.

In MySQL, I would write a query as follows to sort the data by two columns:

SELECT product, qty FROM stock ORDER BY qty DESC, LENGTH(product) DESC 

However, in this case, I need to perform this sorting logic with php. Specifically, the rows are sorted first by descending qty, and then by the length of name descending.

Unsorted Input:

[
    ['name' => 'foo bar', 'qty' => 6],
    ['name' => 'foo bar bar foo', 'qty' => 10],
    ['name' => 'b', 'qty' => 5],
    ['name' => 'foo', 'qty' => 10],
    ['name' => 'bar', 'qty' => 6],
    ['name' => 'foo bar bar bar foo', 'qty' => 6],
]

After sorting, I need to restructure the data with the name values as keys and the qty values as values of a flat, associative array
The finished array would look something like this:

Desired Output:

[
    'foo bar bar foo' => 10,
    'foo' => 10,
    'foo bar bar bar foo' => 6,
    'foo bar' => 6,
    'bar' => 6,
    'b' => 5
]

Answer 1

Looking at the answers to this question: PHP array multiple sort – by value then by key?, it seems array_multisort is the way to go. (I’m not really sure how array_multisort works, I just kinda hacked this up, and it seems to work).

Try this:

$arr = array(
  'foo bar' => 6,
  'foo' => 10,
  'bar' => 6,
  'b' => 5,
  'foo bar bar bar foo' => 6,
  'foo bar bar foo' => 10
);

array_multisort(array_values($arr), SORT_DESC,
  array_map(create_function('$v', 'return strlen($v);'), array_keys($arr)),
  SORT_DESC, $arr);

Demo: http://codepad.org/mAttNIV7

UPDATE: Added array_map to make it sort by the length of the string, before it was just doing:

$str1 > $str2 instead of strlen($str1) > strlen($str2).

UPDATE 2: In PHP >= 5.3, you can replace create_function with a real anonymous function.

array_map(function($v){return strlen($v);}, array_keys($arr))

Demo 2: http://codepad.viper-7.com/6qrFwj