Collecting data from different positions in a given array

Question

I'm writing a PHP function to collect data from different positions in a given array. I've done it as follows which gives me what I require.

for ($a=9; $a < 13; $a++) {
     $n = $arr[$a][2];
     $p = $arr[$a][3];
     $c = $p;
     $v1[] = array($n,$p,$c);
}

for ($b=3; $b < 16; $b+=4) {
 $h = $arr[6][$b];  
     $m = $arr[5][$b]; 
     $l = $arr[4][$b];
     $v2[] = array($h,$m,$l);
}

foreach ($v1 as $k=>$o) {
    $r[] = array( 'na'=> $o[0], 'pr'=> $o[1], 'cu' => $o[2], 'val1' => $v2[$k][0], 'val2' => $v2[$k][1], 'val3' => $v2[$k][2]);
}

To get the output in this format, without repeating the fields:

[0] = > Array 
           [na] => Text 
           [pr] => 1
           [cu] => Text
           [val1] => 1
           [val2] => 2
           [val3] => 3

[1] = > Array 
           ....
           ....

[3] = > Array
           [na] => Text3 
           [pr] => 1-3
           [cu] => Text-22
           [val1] => 101
           [val2] => 22
           [val3] => 34

Is there a better, more efficient way to do this?

Answer 1

Should work (at least it doesn't look like a riddle anymore:)

for ($i = 0; $i < 4; $i++) {
    $a = $i + 9;
    $b = 3 + $i * 4;

    $r[] = array(
        'na'   => $arr[$a][2],
        'pr'   => $arr[$a][3],
        'cu'   => $arr[$a][3],
        'val1' => $arr[6][$b],
        'val2' => $arr[5][$b],
        'val3' => $arr[4][$b]
    );
}

if $r[..]['cu'] is some function result assign to function call directly.

Answer 2

From the answer of Scott Jungwirth, but a bit optimized :

for ($i=0; $i < 4; $i++)
{
    $a = $i + 9;
    $b = $i*4 + 3;
    $v1[] = array($arr[$a][2],$arr[$a][3],$arr[$a][3]);
    $v2[] = array($arr[6][$b],$arr[5][$b],$arr[4][$b]);
    $r[] = array(
                 'na'   => $o[0],
                 'pr'   => $o[1],
                 'cu'   => $o[2],
                 'val1' => $v2[$i][0],
                 'val2' => $v2[$i][1],
                 'val3' => $v2[$i][2],
                );
}

And i think that replacing the $a and $b variables in the brackets would make the code unreadable. So all credits for Scott Jungwirth, just saying that if you can avoid some useless variable assignment (ie reduce the used memory/time), try to !