Removing successive duplicate occurrences in an array

Question

Is there any way that I can remove the successive duplicates from the array below while only keeping the first one?

The array is shown below:

$a=array("1"=>"go","2"=>"stop","3"=>"stop","4"=>"stop","5"=>"stop","6"=>"go","7"=>"go","8"=>"stop");

What I want is to have an array that contains:

$a=array("1"=>"go","2"=>"stop","3"=>"go","7"=>"stop");

would it be ..."3"=>"go","4"=>"stop" instead of "3"=>"go","7"=>"stop")? — Sean
– Sean, Commented Jul 17, 2013 at 23:37
Is it not possible to consider not putting the duplicates in the array to begin with? — calcinai
– calcinai, Commented Jul 18, 2013 at 0:16

UrGuardian4ngel · Accepted Answer · 2013-07-17 23:34:23Z

9

Successive duplicates? I don't know about native functions, but this one works. Well almost. Think I understood it wrong. In my function the 7 => "go" is a duplicate of 6 => "go", and 8 => "stop" is the new value...?

function filterSuccessiveDuplicates($array)
{
    $result = array();

    $lastValue = null;
    foreach ($array as $key => $value) {
        // Only add non-duplicate successive values
        if ($value !== $lastValue) {
            $result[$key] = $value;
        }

        $lastValue = $value;
    }

    return $result;
}

answered Jul 17, 2013 at 23:34

UrGuardian4ngel

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Comments

calcinai · Accepted Answer · 2013-07-17 23:24:39Z

1

You can just do something like:

if(current($a) !== $new_val)
    $a[] = $new_val;

Assuming you're not manipulating that array in between you can use current() it's more efficient than counting it each time to check the value at count($a)-1

answered Jul 17, 2013 at 23:24

calcinai

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2 Comments

Abbasi Over a year ago

can you further elaborate on $new_val where would it come from?

calcinai Over a year ago

$new_val would be the value you're adding eg. "stop" or "go"

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