sort object by integer key in PHP

Question

I have an array with ID's as the key and a name from a database associated with it. I use this to get statistics from PHP for output to a Google Chart generated in JavaScript (through JSON). In PHP I have the following array:

$a = [ 
  '33' => 'first',
  '25' => 'second',
  '14' => 'last
];

If I run the following code:

foreach( $a as $key => $val )
   echo "$key => $val" . PHP_EOL;

I get the following (expected) result

   33 => first
   25 => second
   14 => last

I use AJAX and JSON to send this to a JavaScript environment, here it becomes an object. Now when I run the following JavaScript:

for( var i in a )
   console.log( i + " => " + a[i] );

I get

   14 => last
   25 => second
   33 => first

so my keys are interpreted as integers and sorted in JavaScript, which in this case means the array with statistics I was sending to Google Chart is matching up with the wrong labels.

I solved this by sorting the array in PHP before I read the statistics from the database. I needed the keys to stay the same though, this is what I did in PHP:

 $tmp = array_flip( $a );
 asort( $tmp );
 $a = array_flip( $tmp );

this gives me the array in PHP like this:

[
   '14' => 'last',
   '25' => 'second',
   '33' => 'first'
]

so now a foreach in PHP will have the same order as a for( i in ...) in JavaScript. I was wondering if there is either a nicer way of sorting my array in PHP instead of flipping it twice -or- if there's an option for a loop in JavaScript that doesn't order the (admittedly confusing) integer value keys of my array?

Anyway, wouldn't you prefer making something so that the array isn't sorted on JS side and you can loop through it the way it was supposed to be? — diego nunes, Jul 23 '16 at 03:01
yes, that's why I posted the whole case here. I was a bit bummed out that PHP's foreach was so different from JavaScripts for( var i in... — patrick, Jul 23 '16 at 03:03
Some browsers implements objects/arrays with key-sorting and there is nothing you can do to change that. You can, however, use an array (with pairs inside) rather than an object. — diego nunes, Jul 23 '16 at 03:23

score 2 · Accepted Answer · edited May 23 '17 at 12:15

Have you tried ksort?

ksort

(PHP 4, PHP 5, PHP 7) ksort — Sort an array by key

Description

bool ksort ( array &$array [, int $sort_flags = SORT_REGULAR ] ) Sorts an array by key, maintaining key to data correlations. This is useful mainly for associative arrays.

If it doesn't deal well with numeric-strings keys you can use uksort and write your compare function with a parseInt and spaceship operator (<=>).

If you, however, want to simply stop the reordering fully, altought you can't stop the "sorting" of the object by its keys (and note that it is not standard and is browser-dependent: not all of them will sort it), you can always use pairs inside an array to avoid changes to your original order of elements (pairs, in this case):

$a = [ ['33', 'first'], ['25', 'second'], ['14', 'last'] ];

Nice one. Those pairs are indeed a good way to get around this sorting! — patrick, Jul 23 '16 at 04:37

score 1 · Answer 2 · answered Jul 23 '16 at 02:55

1

All you need:

ksort($a)

Result:

[
    14 => 'last',
    25 => 'second',
    33 => 'first',
]

answered Jul 23 '16 at 02:55

BeetleJuice

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that makes a lot more sense... In one attempt I tried this and killed the index with it (ended up with [0=>'last', 1=>'second', etc).. I tried this again and it worked. I must have done something wrong that first time. Thanks for this answer! – patrick Jul 23 '16 at 02:59

sort object by integer key in PHP

2 Answers2