PHP: How to flatten a multidimensional array by duplicate values

Question

I have the following array:

array(3) {
  [0]=>
  array(2) {
    ["label"]=> string(10) "Chardonnay"
    ["value"]=> int(245)
  }
  [1]=>
  array(2) {
    ["label"]=> string(10) "Chardonnay"
    ["value"]=> int(33)
  }
  [2]=>
  array(2) {
    ["label"]=> string(10) "Chardonnay"
    ["value"]=>int(175)
  }
  [3]=>
  array(2) {
    ["label"]=> string(10) "Stein"
    ["value"]=>int(195)
  }
}

How would I go about "filtering" this array so that it looks like this:

array(2) {
  [0]=>
  array(2) {
    ["label"]=> string(5) "Chardonnay"
    ["value"]=> int(245)
  }
  [1]=>
  array(2) {
    ["label"]=> string(10) "Stein"
    ["value"]=>int(195)
  }
}

So in essence, I want to remove array elements by value where the value is not unique.

I don't even know where to start. Please assist?

@AbraCadaver Just happens to be the first one in the array of duplicates. In the end the site will simply display "Active Filters: Chardonnay, Stein" — Jacques
– Jacques, Commented May 12, 2020 at 14:02

AbraCadaver · Accepted Answer · 2020-05-12 14:08:14Z

2

Since keys must be unique, you can index on the label and you will only have one of each:

$result = array_column($array, null, 'label');

If you just want a single dimension with unique values, extract all labels and then make it unique:

$result = array_unique(array_column($array, 'label'));

If this array is coming from a database query then you would do it in the query instead.

edited May 12, 2020 at 14:08

answered May 12, 2020 at 14:03

AbraCadaver

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2 Comments

Jacques Over a year ago

Perfect mate, thanks. Will mark as correct as soon as the timer allows me.

AbraCadaver Over a year ago

Try both, the second one may give you something easier to work with if you don't need the value keys.

Felippe Duarte · Accepted Answer · 2020-05-12 14:09:31Z

1

You can use this code:

<?php

$arr = [
    [
        "label"=> "Chardonnay",
        "value"=> 245,
    ],
    [
        "label"=> "Chardonnay",
        "value"=> 33,
    ],
    [
        "label"=> "Chardonnay",
        "value"=> 75,
    ],
    [
        "label"=> "Stein",
        "value"=> 195,
    ],
];


$arr = array_intersect_key($arr,array_unique(array_column($arr,'label')));
print_r($arr);

It will remove duplicates, then intersect the keys (0,3 in this case) with the original array. An alternative to preserve the original keys.

answered May 12, 2020 at 14:09

Felippe Duarte

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