PHP- How do I reduce array based on a key's value

Question

I have an array like this:

Array
(
    [0] => Array
        (
            [CommodityID] => 10
            [RetailerID] => 1798
            [Name] => Petrol
            [City] => Parow
            [Line1] => 49 Fifth Avenue
            [Line2] => 
            [Line3] =>  
            [ContractorName] => BP Fifth Ave Motors Parow
            [AreaCode] => 021
            [Number] => 9305025
            [Latitude] => -33.896493
            [Longitude] => 18.579302
            [LogoUrl] => https://webservices.test.com/ContractorLogos/bp.png
            [dist] => 0.00
        )

    [1] => Array
        (
            [CommodityID] => 10
            [RetailerID] => 1798
            [Name] => Petrol
            [City] => Parow
            [Line1] => 49 Fifth Avenue
            [Line2] => 
            [Line3] =>  
            [ContractorName] => BP Fifth Ave Motors Parow
            [AreaCode] => 021
            [Number] => 9305025
            [Latitude] => -33.896493
            [Longitude] => 18.579302
            [LogoUrl] => https://webservices.test.com/ContractorLogos/bp.png
            [dist] => 0.00
        )

    [2] => Array
        (
            [CommodityID] => 22
            [RetailerID] => 1758
            [Name] => Jewellers
            [City] => Parow
            [Line1] => Shop 4
            [Line2] => Mc Intyre Square
            [Line3] => Mc Intyre Road
            [ContractorName] => Du Plessis Manufacturing Jewellers Parow
            [AreaCode] => 021
            [Number] => 9300788
            [Latitude] => -33.895200
            [Longitude] => 18.586710
            [LogoUrl] => https://webservices.test.com/ContractorLogos/DuPlessisJewellers.png
            [dist] => 0.01
        )
)

I simply want to have only unique [RetailerID] i.e:

Array
(
    [0] => Array
        (
            [CommodityID] => 10
            [RetailerID] => 1798
            [Name] => Petrol
            [City] => Parow
            [Line1] => 49 Fifth Avenue
            [Line2] => 
            [Line3] =>  
            [ContractorName] => BP Fifth Ave Motors Parow
            [AreaCode] => 021
            [Number] => 9305025
            [Latitude] => -33.896493
            [Longitude] => 18.579302
            [LogoUrl] => https://webservices.test.com/ContractorLogos/bp.png
            [dist] => 0.00
        )

    [1] => Array
        (
            [CommodityID] => 22
            [RetailerID] => 1758
            [Name] => Jewellers
            [City] => Parow
            [Line1] => Shop 4
            [Line2] => Mc Intyre Square
            [Line3] => Mc Intyre Road
            [ContractorName] => Du Plessis Manufacturing Jewellers Parow
            [AreaCode] => 021
            [Number] => 9300788
            [Latitude] => -33.895200
            [Longitude] => 18.586710
            [LogoUrl] => https://webservices.test.com/ContractorLogos/DuPlessisJewellers.png
            [dist] => 0.01
        )
)

I have tried array_unique, but that seems to make it unique based on all columns. Is there a php built-in function that can do this by looking at just one array key's value?

Possible duplicate: [stackoverflow.com/questions/6057151/… — Gijs de Jong
– Gijs de Jong, Commented Jun 22, 2017 at 11:38
Possible duplicate of Multidimensional array unique based on value (not array key) — B. Desai
– B. Desai, Commented Jun 22, 2017 at 11:42

Ben Yitzhaki · Accepted Answer · 2017-06-22 11:39:03Z

1

would iterate the array once and save only unique values by that field once, for example:

$newArray = array();
foreach($array as $item) {
$newArray[$item['RetailerID']] = $item;
}

this will always save only the last item of the same kind. you can modify the logic to match your needs. another, more safe possibility would be saving the unique values and checking them:

$exists = array();
$newArray = array();
    foreach($array as $item) {
    if(!in_array($item['RetailerID'],$exists)){
       $newArray[$item['RetailerID']] = $item;
       $exists[] = $item['RetailerID'];
     }

    }

answered Jun 22, 2017 at 11:39

Ben Yitzhaki

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1 Comment

Jacques Over a year ago

Thank you sir. Worked great.

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