Sort multi-dimensional array key=>value

scrupul0us

Whats the most efficient way to alphabetically sort the key=> value pairs inside a 2d array?

e.g

Array
(
    [0] => Array
        (
            [key] => value
            [this] => value
            [word] => value
            [blah] => value
            [foo] => value
            [bar] => value
        )
    [1] => Array
        (
            [key] => value
            [this] => value
            [word] => value
            [blah] => value
            [foo] => value
            [bar] => value
        )
)

running a bit late here and thee old noggin isn't firing on all its cylinders

thanks

bradgrafelman

Well.. I'm a bit perplexed. I would've thought that the answer would be to use [man]array_walk/man to apply [man]ksort/man to each sub-array, but I can't for the life of me figure out why I'm getting the results I'm getting.

Test script:

$test = array(
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6'),
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6')
);

array_walk($test, 'ksort');

print_r($test);

Output:

Array
(
    [0] => Array
        (
            [bar] => value6
            [blah] => value4
            [foo] => value5
            [key] => value1
            [this] => value2
            [word] => value3
        )

[1] => Array
    (
        [foo] => value5
        [bar] => value6
        [blah] => value4
        [word] => value3
        [this] => value2
        [key] => value1
    )

)

For whatever reason, the $test[1] array isn't being sorted properly. What's more is that you can add any variable number of similar arrays, e.g.:

$test = array(
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6'),
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6'),
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6'),
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6'),
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6'),
	array('key' => 'value1', 'this' => 'value2', 'word' => 'value3', 'blah' => 'value4', 'foo' => 'value5', 'bar' => 'value6')
);

and all of the arrays - except the one in $test[1] will be sorted correctly:

Array
(
    [0] => Array
        (
            [bar] => value6
            [blah] => value4
            [foo] => value5
            [key] => value1
            [this] => value2
            [word] => value3
        )

[1] => Array
    (
        [foo] => value5
        [bar] => value6
        [blah] => value4
        [word] => value3
        [this] => value2
        [key] => value1
    )

[2] => Array
    (
        [bar] => value6
        [blah] => value4
        [foo] => value5
        [key] => value1
        [this] => value2
        [word] => value3
    )

[3] => Array
    (
        [bar] => value6
        [blah] => value4
        [foo] => value5
        [key] => value1
        [this] => value2
        [word] => value3
    )

[4] => Array
    (
        [bar] => value6
        [blah] => value4
        [foo] => value5
        [key] => value1
        [this] => value2
        [word] => value3
    )

[5] => Array
    (
        [bar] => value6
        [blah] => value4
        [foo] => value5
        [key] => value1
        [this] => value2
        [word] => value3
    )

)

Unless anyone here would care to explain why, I'm about ready to open a bug report over at php.net!

scrupul0us

ok good, so it's not just me who is perplexed as well with the outcome...

bradgrafelman

No, I definitely felt that the problem was PHP's fault; hopefully we'll soon find out.

scrupul0us

well i certainly appreciate the help and follow through... i'll have to keep and eye out on the bug report

scrupul0us

well some nice person updated the bug report

RTFM on ksort() and what it's paremeters are..

i looked, didnt help me any

bradgrafelman

I haven't had a chance to delve into it deeper either. Obviously, you'll have to use a workaround, something like:

foreach($array as $key => $value)
    ksort($array[$key]);

scrupul0us

just another shining example of a useless follow up on a bug report... i wish people weren't so arrogant sometimes:xbones:

ill give it a go brad, thanks🙂

scrupul0us

hey brad did you ever have a moment to futz with this?

the foreach works just fine, but id still love to know why array_walk was acting up

now, the feedback was to RTFM on ksort... I read up on that and sorts additional flags but nothing seems to change the output we experienced

bradgrafelman

D'oh! I finally get it after taking the time to... ironically... RTFM.

It all starts here at [man]array_walk/man's second parameter:

PHP Manual wrote:
Typically, funcname takes on two parameters. The array parameter's value being the first, and the key/index second.

Which translates to "0", "1", "2", etc. being sent as a second parameter to [man]ksort/man in our example above with each call to sort the sub-arrays.

The problem only occurs at index #1 because the constant SORT_NUMERIC happens to be defined with an integer value of 1 ([man]var_dump/man can confirm this). So, all of the other array indexes looked fine because as you'll note in the manual for [man]ksort/man, all of the SORT_ constants (other than numeric!) sort the strings as we expected - as strings (in one way or another).

The solution is to either create your own function using [man]create_function/man or use a foreach (like my workaround above).