array_multisort 2d array

[cannondale]

Guy's

I am trying to understand how to sort a 2 column (2d) array by the second column. My code is below but doesn't sort properly. What am I missing?

$test_ar = array();

$test_ar[0][0] = "b";
$test_ar[0][1] = "2";
$test_ar[1][0] = "a";
$test_ar[1][1] = "1";
$test_ar[2][0] = "d";
$test_ar[2][1] = "4";
$test_ar[3][0] = "e";
$test_ar[3][1] = "5";		
$test_ar[4][0] = "c";
$test_ar[4][1] = "3";


echo("<pre>");
var_dump($test_ar);
echo("</pre>");


array_multisort($test_ar[1], SORT_ASC, $test_ar[0], SORT_ASC);

echo("<pre>");
var_dump($test_ar);
echo("</pre>");

[Weedpacket]

Well, [font=monospace]$test_ar[0][/font] is the array [font=monospace]["b", "2"][/font] and [font=monospace]$test_ar[1][/font] is the array [font=monospace]["a", "1"][/font]. Neither are the array you want to sort.

Rather than Example 2, your structure is more the transpose - like that in Example 3 of the array_multisort manual page; the columns are named [font=monospace]"volume"[/font] and [font=monospace]"edition"[/font] instead of [font=monospace]0[/font] and [font=monospace]1[/font] as yours are.

As an alternative you might want to look at Example 4 of usort (or 2) - your comparison function can of course be a lot simpler: [font=monospace]return $a-$b;[/font].

[cannondale]

Thanks for the information. I agree that php.net array_multisort example #3 appears to be the way my array is organized. However, the example uses an associative array and not and indexed array. Unfortunately, I tried several syntax variations of this example without success before posting my original message. The issue seems to be to find the correct syntax for the assignments in the foreach loop (red font below) for an indexed database array:

<php>
foreach ($data as $key => $row) {
$volume[$key] = $row['volume'];
$edition[$key] = $row['edition'];
}
</php>

It would appear logical that if array_multisort supports associative database arrays, that it would also support indexed database arrays. Is this accurate?

[Weedpacket]

cannondale wrote:

However, the example uses an associative array and not and indexed array

I noted as much:

Weedpacket wrote:

the columns are named "volume" and "edition" instead of 0 and 1 as yours are.

So you'd use 0 and 1 instead of "volume" and "edition". And of course you'd use variable names that are more appropriate for your purposes 🙂

Incidentally, as I also alluded, using [man]usort[/man] the code would be

usort($test_ar, function($a, $b)
{
    return $a[1] - $b[1];
});

[cannondale]

Thanks for the additional information. I tried using the indexed notation in the foreach loop as you suggested.

So you'd use 0 and 1 instead of "volume" and "edition".

However, I get the following message: Warning: array_multisort(): Array sizes are inconsistent

Code below.

$test_ar = array();

$test_ar[0][0] = "b";
$test_ar[0][1] = "2";
$test_ar[1][0] = "a";
$test_ar[1][1] = "1";
$test_ar[2][0] = "d";
$test_ar[2][1] = "4";
$test_ar[3][0] = "e";
$test_ar[3][1] = "5";		
$test_ar[4][0] = "c";
$test_ar[4][1] = "3";


foreach($test_ar AS $row){
	$col0[$key] = $row[0];
	$col1[$key] = $row[1];	
}

array_multisort($col1, SORT_ASC, $col0, SORT_ASC, $test_ar);  

[bradgrafelman]

Where do you define $key?

[cannondale]

Sorry. foreach should be

foreach($test_ar AS $key =>$row)