How to find average from array in php?

Question

Example:

$a[] = '56';
$a[] = '66';
$a[] = '';
$a[] = '58';
$a[] = '85';
$a[] = '';
$a[] = '';
$a[] = '76';
$a[] = '';
$a[] = '57';

Actually how to find average value from this array excluding empty. please help to resolve this problem.

You should not define integers as strings. Instead of `$a[] = '56';` it should be `$a[] = 56;` — Avatar, Jun 06 '19 at 07:23

Mubin · Accepted Answer · 2019-10-15T19:36:27.807

163

first you need to remove empty values, otherwise average will be not accurate.

so

$a = array_filter($a);
$average = array_sum($a)/count($a);
echo $average;

DEMO

More concise and recommended way

$a = array_filter($a);
if(count($a)) {
    echo $average = array_sum($a)/count($a);
}

See here

edited Oct 15 '19 at 19:36

answered Nov 01 '15 at 11:04

Mubin

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8

Keep in mind that you should first check to ensure count() is positive, otherwise you'll get a divide by zero error – Shane N Oct 05 '17 at 21:14
9

array_filter would remove zeros also, skewing the average. – Milo LaMar Mar 23 '19 at 08:49
1

@MiloLaMar: yes, for that please check Don't Panic's answer below. – Mubin Mar 23 '19 at 13:13
You should make `count` check AFTER you've filtered out empty values – Oleg Jul 26 '19 at 05:24
The double use of the `count()` an add some needless overhead from calling `count()` multiple times. You can either do `$count = count($a);` or just do `if($a)`. Both are good enough solutions. I would use `if($a)` which saves on calling `count()` on empty arrays, but is harder to understand for those starting to learn the language. – Ismael Miguel Jun 29 '20 at 10:37

score 26 · Answer 2 · answered May 01 '17 at 19:47

26

The accepted answer works for the example values, but in general simply using array_filter($a) is probably not a good idea, because it will filter out any actual zero values as well as zero length strings.

Even '0' evaluates to false, so you should use a filter that explicitly excludes zero length strings.

$a = array_filter($a, function($x) { return $x !== ''; });
$average = array_sum($a) / count($a);

answered May 01 '17 at 19:47

Don't Panic

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With PHP 7.4+, you can do `array_filter($a, fn($x)=>$x !== '');`, using the syntax for [arrow function](https://www.php.net/manual/en/migration74.new-features.php#migration74.new-features.core.arrow-functions). – Ismael Miguel Jun 29 '20 at 10:40

Martyn Shutt · Answer 3 · 2015-11-01T11:05:48.247

7

echo array_sum($a) / count(array_filter($a));

edited Nov 01 '15 at 11:05

answered Nov 01 '15 at 11:02

Martyn Shutt

1,671
18
25

you need to do count(array_filter($a)) in order to not include the empty values. – JimL Nov 01 '15 at 11:02

score 1 · Answer 4 · answered Sep 11 '20 at 00:55

As a late look, item controls should be done with numeric check. Otherwise something like this $array = [1.2, 0.33, [123]] will corrupt the calculation:

// Get numerics only.
$array = array_filter($array, fn($v) => is_numeric($v));

// Get numerics only where value > 0.
$array = array_filter($array, fn($v) => is_numeric($v) && ($v > 0));

Finally:

public static function average(array $array, bool $includeEmpties = true): float
{
    $array = array_filter($array, fn($v) => (
        $includeEmpties ? is_numeric($v) : is_numeric($v) && ($v > 0)
    ));

    return array_sum($array) / count($array);
}

Credits: froq.util.Arrays

How to find average from array in php?

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