Sum 3rd level column values grouping by 1st level keys in a 3d array

Question

I want to convert the following 3-level array to a flat, associative array of columnar sums per first level key. Do I need to use a foreach() or can array_sum() do this?

[
    'Sum_1' => [
        ['e' => 1000001, 'u' => 'Test1', 'a' => 775.00],
        ['e' => 26, 'u' => 'Test2', 'a' => 555.00],
    ],
    'Sum_2' => [
        ['e' => 1000001, 'u' => 'Test1', 'a' => 110.00],
    ],
    'Sum_3' => [
        ['e' => 1000001, 'u' => 'Test1', 'a' => 444.00],
    ],
]

I want to get the sum of element [a] of each section (e.g. Sum_1, Sum_2, Sum_3).

Desired result:

[
    'Sum_1' => 1330.00,
    'Sum_2' => 110.00,
    'Sum_3' => 444.00,
]

Pierre de LESPINAY · Accepted Answer · 2014-08-22 12:47:51Z

6

You could do like this:

$ret = array_map(function($val) {
  return array_sum(array_map(function($val) {
     return $val['a'];
  }, $val));
}, $array);

Prior to php 5.4:

function a_getter($val) {
    return $val['a'];
}
$ret = array_map(function($val) {
    return array_sum(array_map('a_getter', $val));
}, $array);

edited Aug 22, 2014 at 12:47

Pierre de LESPINAY

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answered Sep 7, 2012 at 4:32

xdazz

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3 Comments

Les_Salantes Over a year ago

@xdazz I was able to do the sums without an array, on the template itself. Thank you anyway. I don't really understand your method. I know what array_map and array_sum do, but can't really understand how they are used in your code? can you explain a bit or direct me to a useful source? Thank you

xdazz Over a year ago

@ThiliniIW Check how array_map work will be help. array_map — Applies the callback to the elements of the given arrays

Pierre de LESPINAY Over a year ago

"Callables" can be used from php 5.4

mickmackusa · Accepted Answer · 2024-01-12 20:35:37Z

0

Make mapped calls of array_sum() on the a column values of each data subset.

Code: (Demo)

var_export(
    array_map(
        fn($rows) => array_sum(
            array_column($rows, 'a')
        ),
        $array
    )
);

Or use nested loops and perform basic arithmetic on the nominated column values. Remember to default the key's value to 0 if it has not yet been pushed into the result array -- this avoids PHP Warnings.

Code: (Demo)

$result = [];
foreach ($array as $k => $rows) {
    foreach ($rows as ['a' => $a]) {
        $result[$k] = ($result[$k] ?? 0) + $a;
    }
}
var_export($result);

answered Jan 12, 2024 at 20:35

mickmackusa♦

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Comments

mickmackusa · Accepted Answer · 2024-01-12 20:38:44Z

0

Using a foreach loop, you can try this:

$sums=array();
foreach($ArrayOfSums as $Offset=>$ArrayOfResults){
    foreach($ArrayOfResults as $ResultOffset=>$Result){
        $sums[$Offset]+=$Result["a"];
    }
}

Result:

Warning: Undefined array key "Sum_1"

Warning: Undefined array key "Sum_2"

Warning: Undefined array key "Sum_3"
array (
  'Sum_1' => 1330.0,
  'Sum_2' => 110.0,
  'Sum_3' => 444.0,
)

edited Jan 12, 2024 at 20:38

mickmackusa♦

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answered Sep 7, 2012 at 4:41

Gntem

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