Multidimensional array unique based on value (not array key)

Question

I have a multidimensional array which I need to be sorted with uniqueness as I have duplicated records, so I need array_unique to go through the array and remove duplicates by the value, e.g.

Array
(
    [0] => Array
        (
            [id] => 324
            [time_start] => 1301612580
            [level] => 0.002
            [input_level] => 0.002
        )

    [1] => Array
        (
            [id] => 325
            [time_start] => 1301612580
            [level] => 0.002
            [input_level] => 0.002
        )

    [2] => Array
        (
            [id] => 326
            [time_start] => 1301612580
            [level] => 0.002
            [input_level] => 0.002
        )
)

There are duplicated time_start, which they are all the same, also level and input_level but they are not to be affected, only if there are matching time_start it should remove it and process the whole array (the array is bigger than you think, but I just posted a small example of the array). Should remove dupes and return like this:

Array
(
    [0] => Array
        (
            [id] => 324
            [time_start] => 1301612580
            [level] => 0.002
            [input_level] => 0.002
        )
)

Questions I've found that didn't work:

hsz · Accepted Answer · 2011-05-19T10:37:19.793

9

$input = array( /* your data */ );
$temp  = array();
$keys  = array();

foreach ( $input as $key => $data ) {
    unset($data['id']);
    if ( !in_array($data, $temp) ) {
        $temp[]     = $data;
        $keys[$key] = true;
    }
}

$output = array_intersect_key($input, $keys);

or

$input = array( /* your data */ );
$temp  = $input;

foreach ( $temp as &$data ) {
    unset($data['id']);
}

$output = array_intersect_key($input, array_unique($temp));

edited May 19 '11 at 10:37

answered May 19 '11 at 10:29

hsz

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Your keys are going to wind up being the array indexes, not the individual associative field names. – John Green May 19 '11 at 10:36
I think the op only cares about a single field, not 'everything except id'. Also... not to cast dispersions here... but does array_unique work that way? I thought it basically used a strict equality internally, which would preclude its usage for comparing arrays of this nature. – John Green May 19 '11 at 10:41
Ok, I looked it up. It appears to use string equality for checking. Which doesn't quite make sense in this context, until I read this: Note: Note that array_unique() is not intended to work on multi dimensional arrays. -- This is an array of associative arrays. Any which way, the use of array_unique scares me. : ) – John Green May 19 '11 at 10:47
Ok good. It works, but the array keys are not indexed properly which I need to use the array in a `for` loop, the keys are skipped like `[0], [12], [18]` etc. – MacMac May 19 '11 at 11:00
Because of it got the unique arrays by their keys. If you want to renumerate the array just use: `$output = array_values($output)` – hsz May 19 '11 at 11:44

kapa · Answer 2 · 2015-03-09T10:22:46.787

6

$temp = array();
array_filter($yourArray, function ($v) use (&$temp) {
    if (in_array($v['time_start'], $temp)) {
        return false;
    } else {
        array_push($temp, $v['time_start']);
        return true;
    }
});

Uses array_filter() which will filter an array based on the result of a callback (I used an anonymous function which can be used since PHP 5.3). The time_start values are collected into a temporary array.

edited Mar 09 '15 at 10:22

answered May 19 '11 at 10:42

kapa

77,694
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One thing to corrent. *array_filter* returns filtered array and doesn't change array at place (by refference). More info [here](http://php.net/manual/en/function.array-filter.php) – userlond Mar 10 '15 at 04:36

John Green · Answer 3 · 2011-05-19T11:01:48.253

1

I think you'll just have to walk it:

$usedVals = array();
$outArray = array();
foreach ($targetArray as $arrayItem)
{
    if (!in_array($arrayItem['time_start'],$usedVals))
    {
        $outArray[] = $arrayItem;
        $usedVals[] = $arrayItem['time_start'];
    }
}
return $outArray;

edited May 19 '11 at 11:01

answered May 19 '11 at 10:30

John Green

13,241
3
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51

@Darzan As opposed to what? : ) It'll eat more memory than say, the suggestion above... but it really shouldn't be much slower. Plus, there are some logic flaws there that I was about to address. – John Green May 19 '11 at 10:34

score 0 · Answer 4 · answered May 19 '11 at 10:30

0

$uniq = array();
foreach($no_unique as $k=>$v) if(!isset($uniq[$v['time_start']])) $uniq[$v['time_start']] = $v;
$uniq = array_values($uniq);

answered May 19 '11 at 10:30

Danzan

958
5
8

Multidimensional array unique based on value (not array key)

4 Answers4

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