Question

I am trying to create a function which maps a recurring pattern of integers using an array.

As an example if I have a starting array of (0,1,3) and I know that I want to stop the pattern when I hit 15.

The pattern gets incremented by a fixed integer each time (lets say 4) so my final pattern should be..

0
1
3
4 (0 + 4)
5 (1 + 4)
7 (2 + 4)
8 (4 + 4)
9 (5 + 4)
11(7 + 4)
12(8 + 4)
13(9 + 4)
15(11+ 4)

Does anyone have any pointers on how this can be achieved?

My current implementation works but is stupidly inefficient which something like this…

$array = array(0,1,3);
$inc = 4;
$end = end($array);
$final = 15;

while($end < $final)
{
$tmp = array();
foreach($array AS $row)
{
$tmp = $row + $inc;
}
$array = merge($tmp, $array);
$end = end($array);
}

Answer 1

I assume that you want to have all the new values in the same array.
So:

//original array
$values =  array(0, 1, 3);

//incremental value
$inc = 4;
//stop value
$stop = 15;

//set the index counter to the origin
$curr_index = 0;

//while the last value of the array is lower than the stop value
while($values[end($values)] < $stop)
{
    //calculate the new value
    $new_value = $values[$curr_index] + $inc;
    //add the new value to the array
    array_push($values, $new_value);
    //update the index counter
    $curr_index ++;
}

this code should work for any initial value in the array, any incremental value and any stop value.