PHP, Sort Multidimensional Array by Child Array

Question

I need to sort my multidimensional array by a value in the child array. In the array example below, I need to sort the parent arrays by child value "revenue_certificate".

function custom_sort($a, $b) {
    return strcmp($a['revenue_certificate'], $b['revenue_certificate']);
}

usort($data_array, 'custom_sort');

I feel like I'm almost there, but where I simply don't understand is how to reference the child array value of "revenue_certificate".

Array
(
    [0] => Array
        (
            [company_id] => 130
            [company_name] => Eureka / Brookings
            [revenue_certificate] => 3
            [revenue_cash] => 33
            [average_sale] => 0
            [total_orders] => 0
            [certificates_per_order] => -1
            [revenue_per_certificate] => -1
            [visible_items] => 25
            [retail_value] => -1
            [average_discount] => -1
            [new_advertisers] => 1
            [emails_harvested] => 1
            [new_customers] => 1
        )

    [1] => Array
        (
            [company_id] => 82
            [company_name] => Big Deals Across America
            [revenue_certificate] => 1
            [revenue_cash] => 0
            [average_sale] => 0
            [total_orders] => 0
            [certificates_per_order] => -1
            [revenue_per_certificate] => -1
            [visible_items] => 1
            [retail_value] => -1
            [average_discount] => -1
            [new_advertisers] => 0
            [emails_harvested] => 0
            [new_customers] => 0
        )

    [2] => Array
        (
            [company_id] => 134
            [company_name] => Fergus Falls, MN
            [revenue_certificate] => 2
            [revenue_cash] => 20
            [average_sale] => 0
            [total_orders] => 0
            [certificates_per_order] => -1
            [revenue_per_certificate] => -1
            [visible_items] => 128
            [retail_value] => -1
            [average_discount] => -1
            [new_advertisers] => 129
            [emails_harvested] => 2
            [new_customers] => 1
        )

)

Thanks for any help.

your code looks ok, What's the problem? Do you get an error? — Gavriel
– Gavriel, Commented Jan 28, 2016 at 23:48
No error. When running code as originally posted the array is sorted by "revenue_certificate" but it's not treating the value of "revenue_certificate" as a number, rather a string. For instance, this might be the resulting order: 0, 10, 11000, 125, 1350, 20 — Jeff Walden
– Jeff Walden, Commented Jan 28, 2016 at 23:54

Gavriel · Accepted Answer · 2016-01-28 23:59:51Z

1

Don't use strcmp :)

function custom_sort($a, $b) {
    return $a['revenue_certificate'] - $b['revenue_certificate'];
}

usort($data_array, 'custom_sort');

custom_sort should return a negative, 0, positive value when $a < $b, $a == $b, $a < $b respectively (just as strcmp does BTW).

edited Jan 28, 2016 at 23:59

answered Jan 28, 2016 at 23:55

Gavriel

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1 Comment

Jeff Walden Over a year ago

Worked great! Follow-up though, how does this actually work? It looks like it's just subtracting one array value from another.

Eric · Accepted Answer · 2016-01-28 23:50:51Z

0

I believe you need to use ksort instead

Sorts an array by key, maintaining key to data correlations. This is useful mainly for associative arrays.

answered Jan 28, 2016 at 23:50

Eric

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2 Comments

Nick Zuber Over a year ago

ksort looks like it sorts the keys instead of OP's problem where he needs to sort his array based on values of a particular key. Am I misunderstanding the problem at hand and/or your solution?

Eric Over a year ago

check out the note by DavidG, it seems like this is what OP needs. I could be mistaken though

VnoitKumar · Accepted Answer · 2020-07-22 14:32:49Z

0

Array ( [0] => Array ( [India] => 2 ) [1] => Array ( [Canada] => 1 ) [2] => Array ( [USA] => 3 ) )

also sort this desc order according to country value

edited Jul 22, 2020 at 14:32

VnoitKumar

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answered Jul 22, 2020 at 5:09

Sunilvishwakarma

1

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