Finding patterns in php array

Question

For example:

main array is: array(0 => 'A', 1 => 'A', 2 => 'B', 3 => 'B', 4 => 'B');

pattern is: array('A', 'B');

expected answer: array( array(0, 2), array(1, 3) )

one more example:

main array array(0 => 'F', 5 => 'G', 78 => 'R', 2 => 'D');

pattern array('G', 'R', 'F');

expected answer: array(array(5, 78, 0))

How can I find all occurrences of pattern in array?

@Rocket I think it is makes more sense to think of it as array( 'A' => array( 0, 2 ), 'B' => array( 1, 3 ) ) — sean
– sean, Commented Jul 10, 2012 at 16:03
@Rocket it's ids of pattern matched elements. In example there is two matched pairs -> (0,2) (1,3) — Yekver
– Yekver, Commented Jul 10, 2012 at 16:03
@Yekver: So for array(0, 2). The 0 is the index of A in the pattern array. and 2 is the number of As in the main array? — gen_Eric
– gen_Eric, Commented Jul 10, 2012 at 16:06
@Rocket: nope, for array(0, 2) the 0 is the index of A in the main array, and 2 is the index of B in the main array — Yekver
– Yekver, Commented Jul 10, 2012 at 16:10

gen_Eric · Accepted Answer · 2012-07-10 16:29:06Z

2

Here's an function that uses recursion.

function array_pattern($array, $pattern){
    $ret = array(array());
    $found = true;
    foreach($pattern as $val){
        $x = array_search($val, $array);
        if($x === FALSE){
            $found = FALSE;
            break;
        }
        unset($array[$x]);
        $ret[0][] = $x;
    }
    return $found ? array_merge($ret, array_pattern($array, $pattern)) : array();
}

Call it like this:

$a = array_pattern(array(0 => 'A', 1 => 'A', 2 => 'B', 3 => 'B', 4 => 'B'), array('A', 'B'));
$b = array_pattern(array(0 => 'F', 5 => 'G', 78 => 'R', 2 => 'D'), array('G', 'R', 'F'));

DEMO: http://codepad.org/JCdsAMGk

edited Jul 10, 2012 at 16:29

answered Jul 10, 2012 at 16:23

gen_Eric

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Comments

Tucker · Accepted Answer · 2012-07-10 16:25:25Z

0

I didn't test the following code, but it may give you ideas.

$arr = array(0 => 'A', 1 => 'A', 2 => 'B', 3 => 'B', 4 => 'B');
$test = array('G', 'R', 'F');

$count = 0;
$count2 = 0; 
for($i=0;$i<count($arr);$++){
    $pass= true;
    if(count($test)+$count <= count($arr)){
        for($k=0;$k<count($test);$k++){
            if($arr[k+i]!=$test[k]){
                  $pass = false;
            }
        }
    }else{
       $pass = false;
    }

     if($pass){
       $output[$count2] = $i;
       $count2++;
     }


}

answered Jul 10, 2012 at 16:25

Tucker

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