Conditional remove adjacent duplicates from array

Question

I have following code that removes adjacent duplicates from the $myArray

<?php
 $myArray = array(
                    0 => 0,
                    1 => 0,
                    2 => 1,
                    5 => 1,
                    6 => 2,
                    7 => 2,
                    8 => 2,
                    9 => 0,
                    10 => 0,
                );

            $previtem= NULL;
            $newArray = array_filter(
                $myArray,
                function ($currentItem) use (&$previtem) {
                    $p = $previtem;
                    $previtem= $currentItem;
                    return $currentItem!== $p ;
                }
            );

echo "<pre>";
print_r($newArray);
?>

It works perfectly fine, but I have to change a condition bit for value 2. That means for other values we can pick first occurrence and ignore the others. But for 2, we need to pick last occurrence and ignore others.

So required output is

Array
(
    [0] => 0 //first occurrence of 0 in $myArray
    [2] => 1 //first occurrence of 1 in $myArray
    [8] => 2 //last occurrence of 2 in the $myArray
    [9] => 0 //first occurrence of 0 in $myArray
)

How to modify my code to achieve above result??

In reality I have multidimensional array, but for better explanation I have used single dimensional array here in the question.

UPDATE My actual array is

$myArray = array(
        0 => array("Value"=>0, "Tax" => "11.00"),
        1 => array("Value"=>0, "Tax" => "12.00"),
        2 => array("Value"=>1, "Tax" => "13.00"),
        5 => array("Value"=>1, "Tax" => "14.00"),
        6 => array("Value"=>2, "Tax" => "15.00"),
        7 => array("Value"=>2, "Tax" => "16.00"),
        8 => array("Value"=>2, "Tax" => "17.00"),
        9 => array("Value"=>0, "Tax" => "18.00"),
        10 => array("Value"=>0, "Tax" => "19.00"),
    );

And my actual code

$previtem= NULL;
$newArray = array_filter(
    $myArray,
    function ($currentItem) use (&$previtem) {
        $p["Value"] = $previtem["Value"];
        $previtem["Value"] = $currentItem["Value"];
        return $currentItem["Value"]!== $p["Value"] ;
    }
);

Thanks

Kevin Hill · Accepted Answer · 2018-06-14 06:15:21Z

1

This should do what you are looking for.

function array_filter($a) {
$na = array();
$first = true;
$p = null;
$wantlast = false;
foreach ($a as $v) {
    if ($wantlast) {
        ($v != $p) ? $na[] = $p: null;
    }
    $wantlast = ($v == 2) ? true : false;
    if (!$wantlast) {
        (($v != $p) || ($first))? $na[] = $v : null;
    }
    $p = $v;
    $first = false;
}
return $na;
}

edited Jun 14, 2018 at 6:15

answered Jun 14, 2018 at 5:46

Kevin Hill

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5 Comments

Kevin Hill Over a year ago

adjusted to match function name to that used by WatsMyName

WatsMyName Over a year ago

Thanks I will check and let you know

WatsMyName Over a year ago

It changes key which I don't want to change.

WatsMyName Over a year ago

I sorted this out. Thanks for the working solution. I will accept your solution because your solution worked perfectly fine with multidimensional array.

Kevin Hill Over a year ago

Thank you. I felt that a stand alone function should better allow you to modify to suit your needs - particularly in light of the fact that your example was a simplified from the real use case - sorting an array. In the case of not modifying the key, update the foreach to "foreach (a as $k => $v)" - record the key in the same places, and use it when storing.

Rakesh Sojitra · Accepted Answer · 2018-06-14 06:21:11Z

1

$myArray = array(
        0 => 0,
        1 => 0,
        2 => 1,
        5 => 1,
        6 => 2,
        7 => 2,
        8 => 2,
        9 => 0,
        10 => 0,
    );

$previtem= NULL;
$newArray = array_filter(
    $myArray,
    function ($currentItem, $key) use (&$previtem,$myArray) {
        $p = $previtem;
        if($currentItem != 2){
            $previtem = $currentItem;
        }else{
            $lastkey = array_search(2,(array_reverse($myArray, true)));
            if($key != $lastkey)
                $currentItem = $previtem;
        }
        return $currentItem!== $p ;
    }, ARRAY_FILTER_USE_BOTH
);

echo "<pre>";
print_r($newArray);

answered Jun 14, 2018 at 6:21

Rakesh Sojitra

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2 Comments

WatsMyName Over a year ago

Thanks! Will check this

WatsMyName Over a year ago

What to do in case of multidimensional array?? Like in update in my post above

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