How can I sum all values of a specific array key recursively?

Question

I have an array like this:

Array
(
    [1000] => Array
        (
            [pv] => 36
        )

    [1101] => Array
        (
            [1102] => Array
                (
                    [pv] => 92
                )

            [pv] => 38
        )

    [pv] => 64
)

How I can find the sum of all array elements with key 'pv', regardless of the depth at which they appear?

For this example the result will be 36+92+38+64 = 230

Medoo: stackoverflow.com/questions/3777134/…, stackoverflow.com/questions/3776798/php-array-recursion, ... — Wernight
– Wernight, Commented Sep 23, 2010 at 11:57

salathe · Accepted Answer · 2010-09-24 08:50:37Z

22

Another alternative:

$sum = 0;
$array_obj = new RecursiveIteratorIterator(new RecursiveArrayIterator($array));
foreach($array_obj as $key => $value) {
    if($key == 'pv')
        $sum += $value;
}
echo $sum;

Update: Just thought I'd mention that this method uses the PHP SPL Iterators.

Salathe Edit:

A simple (relatively) way to filter the keys and to sum the values (without writing a custom Iterator) would be to do some filtering with a RegexIterator, convert the resulting iterator into an array and use the handy array_sum function on it. This is purely an academic exercise and I certainly wouldn't advocate it as the best way to achieve this... however, it is just one line-of-code. :)

$sum = array_sum(
    iterator_to_array(
        new RegexIterator(
            new RecursiveIteratorIterator(
                new RecursiveArrayIterator($array)
            ),
            '/^pv$/D',
            RegexIterator::MATCH,
            RegexIterator::USE_KEY
        ),
        false
    )
);

edited Sep 24, 2010 at 8:50

salathe

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answered Sep 23, 2010 at 11:58

Russell Dias

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8 Comments

jwueller Over a year ago

+1! This one is nice, too! It does not require an extra function and does not clutter up the namespace. I like it!

Chris Over a year ago

+1 for IteratorIterator I recently used this for directory traversing to find certain files with the RegexIteratorIterator.

ircmaxell Over a year ago

+1: Plus, you could even toss in a FilterIterator and not have to worry about the `if($key == 'pv')``part... But this is on the mark either way...

salathe Over a year ago

@ircmaxell,@erisco Cue ridiculous one-liner...

$sum = array_sum(iterator_to_array(new RegexIterator(new RecursiveIteratorIterator(new RecursiveArrayIterator($array)), '/^pv$/D', RegexIterator::MATCH,RegexIterator::USE_KEY), false));

ircmaxell Over a year ago

Yeah, that's ridiculous. An awesome display of what you can do with SPL, but still ridiculous.

|

fredley · Accepted Answer · 2010-09-23 11:50:40Z

12

function addPV($array){
  $sum = 0;
  foreach($array as $key => $a){
    if (is_array($a)){
       $sum += addPV($a);
    }else if($key == 'pv') {
       $sum += $a;
    }
  }
  return $sum;
}

answered Sep 23, 2010 at 11:50

fredley

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4 Comments

jwueller Over a year ago

+1! I hate passing function names as string as required for array_reduce(), etc. Nice and clean solution!

Wrikken Over a year ago

@elusive: in PHP5.3 you can just pass anonymous functions (like javascript tends to do), maybe that's less creepy to you: $arr = range(1,40); var_dump(array_reduce($arr,function($v,$k){return $v+$k;}));

jwueller Over a year ago

@Wrikken: Thats right, but you cannot assume that PHP 5.3 is already running everywhere. AFAIK, 5.3 will ship with the next release of debian at the earliest. fredleys solution works nicely with currently used versions of PHP and i consider it less ugly than the array_reduce() method.

Wrikken Over a year ago

Afaik, 5.3.2 is in the testing branch, so in Debian terms that will be 'soonish', and I'm not disputing this is a nice solution (+1 'ed it), just reacted to your 'I don't like to pass function names as string' with some info you might be happy with in future in case you didn't know already ;)

Community · Accepted Answer · 2017-05-23 12:00:43Z

7

based on @Ali Sattari answer

function sum($v, $w) {
    return $v + (is_array($w) ? 
        array_reduce($w, __FUNCTION__) : $w);
}

edited May 23, 2017 at 12:00

CommunityBot

11 silver badge

answered Sep 23, 2010 at 12:05

user187291

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Comments

Ali Sattari · Accepted Answer · 2010-09-23 11:55:27Z

4

you can use array_reduce or array_walk_recursive functions and a custom call back function of yourself:

function sum($v, $w)
{
    $v += $w;
    return $v;
}

$total = array_reduce($your_array, "sum");

answered Sep 23, 2010 at 11:55

Ali Sattari

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1 Comment

jon_darkstar Over a year ago

i like this way, but dont you need conditional to check that key is pv? could be other numerical values

RobertPitt · Accepted Answer · 2010-09-23 12:21:59Z

2

function SumRecursiveByKey($array,$key)
{
    $total = 0;
    foreach($array as $_key => $value)
    {
        if(is_array($value))
        {
            $total += SumRecursiveByKey($array,$key);
        }elseif($_key == $key)
        {
             $total += $value;
        }
    }
    return $total;
}

use like

$summed_items = SumRecursiveByKey($myArray,'pv');

This would give you more leeway in checking alternative keys a swell.

answered Sep 23, 2010 at 12:21

RobertPitt

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Comments

Mark Baker · Accepted Answer · 2010-09-23 11:54:43Z

1

$sum = 0;

function sumArray($item, $key, &$sum)
{
    if ($key == 'pv')
       $sum += $item;
}

array_walk_recursive($array, 'sumArray',&$sum);
echo $sum;

answered Sep 23, 2010 at 11:54

Mark Baker

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2 Comments

fredley Over a year ago

Works as long as there are nothing other than arrays and numbers with the key pv.

Mark Baker Over a year ago

@fredley - if the OP has additional criteria (eg test for booleans, etc) they can easily be added to the sumArray callback function

Auirio · Accepted Answer · 2010-09-23 12:15:55Z

1

$array = array('1000'=> array('pv'=>36), array('1101' => array('pv'=>92)));

$total = 0;
foreach(new recursiveIteratorIterator( new recursiveArrayIterator($array)) as $sub)
{
 $total += (int)  $sub;
}
print_r($total);

answered Sep 23, 2010 at 12:15

Auirio

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Comments

Alex Pliutau · Accepted Answer · 2010-09-23 11:50:07Z

-1

private function calculateUserGv($userId) {
    $group = $this->arrayUnder($this->_user_tree, $userId);
    global $gv;
    $gv = 0;
    $gv    = $this->gvRecursive($group);
    return;
}

private function gvRecursive($group) {
    global $gv;
    foreach ($group as $key => $val) {
        if ($key == 'pv') {
            $gv += $group[$key];
        }
        else {
            $this->gvRecursive($val);
        }
    }
    return $gv;
}

answered Sep 23, 2010 at 11:50

Alex Pliutau

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1 Comment

fredley Over a year ago

having global $gv, modifying it within the function, then return $gv is not nice. Invoking this function with $gv = $this->gvRecursive($group); is not nice at all.

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