PHP sum value of array with conditional

Question

I'm trying to sum value of array and check if value <= less than or equal to 10 then add new index key with value:

source array:

$arr= array(
    'all' => array(
        'db1' => array(
            'val' => 9.4,
            'ran' => 'ex'
        ),
        'db2' => array(
            'val' => 5.2,
            'ran' => 'as'
        ),
        'db3' => array(
            'val' => 2.5,
            'ran' => 'bm'
        ),
        'db4' => array(
            'val' => 7.4,
            'ran' => 'kl'
        ),
        'db5' => array(
            'val' => 2.9,
            'ran' => 'df'
        )
    )
);

result array:

$res = array(
    all => array(
        'db1' => array(
            'val' => 9.4,
            'ran' => 'ex',
            'index' => 1
        ),
        'db2' => array(
            'val' => 5.2,
            'ran' => 'as',
            'index' => 2
        ),
        'db3' => array(
            'val' => 2.5,
            'ran' => 'bm',
            'index' => 2
        ),
        'db4' => array(
            'val' => 7.1,
            'ran' => 'kl',
            'index' => 3
        ),
        'db5' => array(
            'val' => 2.9,
            'ran' => 'df',
            'index' => 3
        )
    )
);

as we can see db1['val'] can't sum with db2['val'] because result will be greater than 10 so add index 1, db2 and db3 is less than 10 so add same index 2 to both of them.

any help or suggestions would be appreciated.

Possibly related, as this appears to be an XY issue: stackoverflow.com/questions/14129023/… — Blue
– Blue, Commented Jul 28, 2019 at 11:18

arkascha · Accepted Answer · 2019-07-28 14:11:01Z

3

Well, you need to walk through the array elements and keep track of your index and sum:

<?php
$data = [
    'db1' => ['val' => 9.4, 'ran' => 'ex'],
    'db2' => ['val' => 5.2, 'ran' => 'as'],
    'db3' => ['val' => 2.5, 'ran' => 'bm'],
    'db4' => ['val' => 7.4, 'ran' => 'kl'],
    'db5' => ['val' => 2.9, 'ran' => 'df']
];

$sum = 0;
$index = 1;
array_walk($data, function(&$entry) use (&$sum, &$index) {
    $sum += $entry['val'];
    if ($sum >= 10) {
        $index++;
        $sum -= 10;
    }
    $entry['index'] = $index;
});

print_r($data);

This variant would even be a bit more compact and also cleaner, but harder to read and a bit risky:

<?php
$data = [
    'db1' => ['val' => 9.4, 'ran' => 'ex'],
    'db2' => ['val' => 5.2, 'ran' => 'as'],
    'db3' => ['val' => 2.5, 'ran' => 'bm'],
    'db4' => ['val' => 7.4, 'ran' => 'kl'],
    'db5' => ['val' => 2.9, 'ran' => 'df']
];

array_walk($data, function(&$entry) use (&$sum, &$index) {
    $sum += $entry['val'];
    if ($sum >= 10) {
        $index++;
        $sum -= 10;
    }
    $entry['index'] = $index + 1;
});

print_r($data);

The obvious output is:

Array
(
    [db1] => Array
        (
            [val] => 9.4
            [ran] => ex
            [index] => 1
        )

    [db2] => Array
        (
            [val] => 5.2
            [ran] => as
            [index] => 2
        )

    [db3] => Array
        (
            [val] => 2.5
            [ran] => bm
            [index] => 2
        )

    [db4] => Array
        (
            [val] => 7.4
            [ran] => kl
            [index] => 3
        )

    [db5] => Array
        (
            [val] => 2.9
            [ran] => df
            [index] => 3
        )

)

edited Jul 28, 2019 at 14:11

answered Jul 28, 2019 at 11:43

arkascha

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2 Comments

ichadhr Over a year ago

this heal my headache over 2 days, will read more about array_walk.. thank you!

arkascha Over a year ago

The important point here is not the array_waslk(...) function, but how to keep track of sum and index. You can do the same using a simple for or foreach loop, but above is easier to read in my eyes, since it clearly encapsulates the process without poluting the calling functions name space.

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