PHP Array, remove only duplicates next to eachother

Question

$arr = array(1, 2, '...', '...', '...', 6, 7, 8, '...', 10);
array_unique creates: array(1, 2, '...', 6, 7, 8, 10);
I want the following: array(1, 2, '...', 6, 7, 8, '...', 10);

So basically, I'm looking for a fast way to remove only duplicates next to eachother.

AFAIK, no out of the box function for it, so write a small looping script. — Wrikken
– Wrikken, Commented Sep 30, 2014 at 15:20

Boann · Accepted Answer · 2014-09-30 15:22:30Z

1

$result = array();
$first = true;
foreach ($array as $x) {
    if ($first || $x !== $previous) $result[] = $x;
    $previous = $x;
    $first = false;
}

Alter the $x !== $previous condition to suit your preferred definition of "duplicate". For example, array_unique does a loosely-typed comparison.

answered Sep 30, 2014 at 15:22

Boann

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2 Comments

Barmar Over a year ago

You need to set $first back to true when you encounter a non-duplicate.

Boann Over a year ago

@Barmar No, that's not what it's for.

Marcin Nabiałek · Accepted Answer · 2014-09-30 15:28:40Z

0

I would do it this way:

<?php

$arr = array(1, 2, '...', '...', '...', 6, 7, 8, '...', 10);

$el = $arr[0];

$out = $arr;

for ($i=1, $c = count($out); $i<$c; ++$i) {
    if ($arr[$i] == $el) {
        unset($out[$i]);
    }
    else {
        $el = $out[$i];
    }
}

$out = array_values($out);

foreach ($out as $i) {
    echo $i."<br />";
}

Output:

1
2
...
6
7
8
...
10

answered Sep 30, 2014 at 15:28

Marcin Nabiałek

112k43 gold badges271 silver badges299 bronze badges

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