Performance: array_max_recursive implementations

performance_array_max_recursive.php

<?php

if (count($argv) > 1) {
    define('NEST_LEVEL', $argv[1]);
    define('NUMBER_OF_TEST_ITERATIONS', $argv[2]);
} else {
    define('NEST_LEVEL', 50);
    define('NUMBER_OF_TEST_ITERATIONS', 5);
}

function MaxArrayA(array $array) {
    $max = NULL;
    $stack = array($array);

    do {
        $current = array_pop($stack );
        foreach ($current as $value) {
            if (is_array($value)) {
                $stack[] = $value;
            } elseif (filter_var($value, FILTER_VALIDATE_INT) !== FALSE) {
                // max(NULL, 0) returns NULL, so cast it
                $max = (int) max($max, $value);
            }
        }

    } while (!empty($stack));

    return $max;
}

function MaxArrayB($arr) {
    $max = NULL;
    array_walk_recursive($arr, function ($current) use (&$max) {
        if (filter_var($current, FILTER_VALIDATE_INT) !== FALSE) {
            $max = max($max, $current);
        }
    });
    return $max;
}
function MaxArrayC($arr) {
    $max = FALSE;
    array_walk_recursive($arr, function ($current) use (&$max) {
        if (is_int($current) && ($current > $max || $max === FALSE)) {
            $max = $current;
        }
    });
    return $max;
}
function MaxArrayD($arr) {
    $max = FALSE;
    foreach ($arr as $value) {
        if (is_array($value)) {
            $max = max($max, MaxArrayD($value));
        } elseif (filter_var($value, FILTER_VALIDATE_INT) !== FALSE) {
            // max(NULL, 0) returns NULL, so cast it
            $max = (int) max($max, $value);
        }
    }
    return $max;
}
function MaxArrayE($arr) {
    $max = FALSE;
    foreach ($arr as $value) {
        if (is_array($value)) {
            $max = max($max, MaxArrayE($value));
        } elseif (is_int($value)) {
            // max(NULL, 0) returns NULL, so cast it
            $max = (int) max($max, $value);
        }
    }
    return $max;
}

$heavilyNestedArray = array(1);
for ($i = 1; $i < NEST_LEVEL; $i++) {
    $heavilyNestedArray[] = $i;
    $heavilyNestedArray[] = $heavilyNestedArray;
}

function testFunction($callable, $array) {
    $startTime = microtime(TRUE);
    $callable($array);
    $timeTaken = microtime(TRUE) - $startTime;
    return $timeTaken;
}

$results = array(
    'a' => array(),
    'b' => array(),
    'c' => array(),
    'd' => array(),
    'e' => array(),
);
for ($i = 0; $i < NUMBER_OF_TEST_ITERATIONS; $i++) {
    $results['a'][] = testFunction('MaxArrayA', $heavilyNestedArray);
    $results['b'][] = testFunction('MaxArrayB', $heavilyNestedArray);
    $results['c'][] = testFunction('MaxArrayC', $heavilyNestedArray);
    $results['d'][] = testFunction('MaxArrayD', $heavilyNestedArray);
    $results['e'][] = testFunction('MaxArrayE', $heavilyNestedArray);
}

$print_result = function ($result, $name) {
    echo "Function '$name' at nest level ", NEST_LEVEL, ' and ' , NUMBER_OF_TEST_ITERATIONS , " iterations:\n";
    echo "Min:" . min($result) . "\n";
    echo "Max:" . max($result) . "\n";
    echo "Average:" . (array_sum($result)/count($result)) . "\n";
    echo str_repeat('=', 40), "\n";
};

echo str_repeat('=', 40), "\n";
array_walk($results, $print_result);