php - Deleting Elements In An Array Only When They Are Next To Each Other -

i have array composed of information looks following:

['jay', 'jay', 'jay', 'spiders', 'dogs', 'cats', 'john', 'john', 'john', 'dogs', 'cows', 'snakes'] 

what i'm trying remove duplicate entries if occur right next each other.

the correct result should following:

['jay', 'spiders', 'dogs', 'cats', 'john', 'dogs', 'cows', 'snakes'] 

i'm using php kind of logic able me out problem.

here code i've tried far:

$clean_pull = array(); $counter = 0; $prev_value = null;  foreach($pull_list $value) {     if ($counter == 0) {         $prev_value = $value;         $clean_pull[] = $value;     }     else {         if ($value != $pre_value) {             $pre_value = value;         }     }     echo $value . '<br>'; } 

francis, when run following code:

$lastval = end($pull_list); ($i=count($pull_list)-2; $i >= 0; $i--){     $thisval = $pull_list[$i];     if ($thisval===$lastval) {         unset($pull_list[$i]);     }     $lastval = $thisval; } # optional: reindex array: array_splice($pull_list, 0, 0);  var_export($pull_list); 

, these results:

array ( 0 => 'nj lefler', 1 => 'deadpool', 2 => 'nj lefler', 3 => 'captain universe: hero you', 4 => 'nj lefler', 5 => 'the movement', 6 => 'nj lefler', 7 => 'the dream merchant', 8 => 'nolan lefler', 9 => 'deadpool', 10 => 'nolan lefler', 11 => 'captain universe: hero you', 12 => 'nolan lefler', 13 => 'the movement', 14 => 'tom smith', 15 => 'deadpool', 16 => 'tom smith', 17 => 'captain universe: hero you', )  

your approach (a $prev_value variable) should work fine , don't need counter.

your use of $counter why code doesn't work--the first half of if statement executed because $counter never incremented; , second half compares values. thing need compare current value previous value , include current value if differs (or remove if it's same).

it's easier see algorithm if use functional reduction. here example using array_reduce:

$a = array('jay', 'jay', 'jay', 'spiders', 'dogs', 'cats', 'john', 'john', 'john', 'dogs', 'cows', 'snakes');  $na = array_reduce($a, function($acc, $item){     if (end($acc)!==$item) {         $acc[] = $item;     }     return $acc; }, array());  var_export($na); 

note comparison of var_export($a) (your original array) , var_export($na) (the result produced code):

$a = array (            $na = array (       0 => 'jay',             0 => 'jay',       1 => 'jay',             1 => 'spiders',   2 => 'jay',             2 => 'dogs',      3 => 'spiders',         3 => 'cats',      4 => 'dogs',            4 => 'john',      5 => 'cats',            5 => 'dogs',      6 => 'john',            6 => 'cows',      7 => 'john',            7 => 'snakes',    8 => 'john',          )                   9 => 'dogs',   10 => 'cows',   11 => 'snakes', ) 

the array_reduce() method same thing following code:

$na = array(); foreach ($a $item) {     if (end($na)!==$item) {         $na[] = $item;     } } 

instead of returning copy of array, can modify array in-place using same algorithm starting end of array:

$lastval = end($a); ($i=count($a)-2; $i >= 0; $i--){     $thisval = $a[$i];     if ($thisval===$lastval) {         unset($a[$i]);     }     $lastval = $thisval; } # optional: reindex array: array_splice($a, 0, 0);  var_export($a);