find max() of specific multidimensional array value in php

Question

See array for example: here

Basically, I want to find the max() for array[]['time'] in that array. I can figure it out if I loop through it, but I was hoping there was a more elegant solution.

• John Carter: possible duplicate of Get the maximum value from an element in a multidimensional array?

Answer 1

Think array_reduce if you want to compute some single value iteratively over an array:

$max = array_reduce($array, function($a, $b) { 
 return $a > $b['time'] ? $a : $b['time']; 
} );

Or you could make use of a utility function like:

function array_col(array $a, $x)
{
 return array_map(function($a) use ($x) { return $a[$x]; }, $a);
}

which would be used like:

$max = max(array_col($array, 'time'));

It's more general purpose and could be used for other similar things.

• Ethan: Couldn't you use PHP's built in array_column function instead of your array_col function? php.net/manual/en/function.array-column.php

Answer 2

Sort the array from highest to lowest in terms of []['time'] and get the first value:

function sort_arr($item_1, $item_2)
{
 return $item_2['time'] - $item_1['time'];
}
usort($arr, 'sort_arr');
// $arr[0] is the item with the highest time

• Marcello Mönkemeyer: I wouldn't recommend using a complex sort algorithm for something like getting a single value out of an array. Actually, sorting should only be done when really needed. The additional overhead isn't worth a "cool-looking" solution.

Answer 3

You could always sort the array and take the first or last value respectively. You can make use of usort to sort your array by providing a custom comparison function to reflect your structure.

Here's a simple example:

$foo[1]["time"] = 2323443;
$foo[2]["time"] = 343435;
$foo[3]["time"] = 13455;
$foo[4]["time"] = 9873634;
$foo[5]["time"] = 82736;
$foo[6]["time"] = 9283;
function cmp($a, $b)
{
 if ($a["time"] == $b["time"]) {
 return 0;
 }
 return ($a["time"] < $b["time"]) 
 ? -1 
 : 1;
}
usort($foo, "cmp");
$max = $foo[count($foo)-1]["time"];