PHP - Patterns within Arrays - php

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

$array = array(0,1,3);
$inc = 4;
$final = 15;
$end = end($array);
while($end < $final)
{
$end += $inc;
$array[] = $end;
}
Or with a for loop:
$array = array(0,1,3);
$inc = 4;
$final = 15;
for($i = end($array) + $inc; $i <= $final; $i += $inc)
{
$array[] = $i;
}

Answer 2

Y'all are missing the fact that 4 is being added to the value in the array 2 keys back, not the last value.
This is the code you need (tested, and working)
$array = array(0,1,3);
$inc = 4;
$end = end($array);
$key = key($array);
$final = 15;
while ($end < $final) {
if ($array[$key-2] >= 0) {
$end = $array[$key-2] + $inc;
$array[] = $end;
$key++;
}
}
I also included in there a check to make sure the key being added to actually exists, though that may not be needed.

Answer 3

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.

Answer 4

<?php
function myArrayFunction(array $array, $inc = 4, $final = 15, $end = null)
{
if(!$end)
{
$end = end($array);
}
while($end < $final)
{
$end += $inc;
$array[] = $end;
}
return $array; //assume you're wanting $array back
}
This is minus any sort of testing or checking of injected values but you get the idea.

Answer 5

It would be better to know what you are trying to achieve here as the whole thing looks horribly overcomplicated, but...
$array = array(0,1,3);
$pattern = array();
$inc = 4;
$final = 15;
for ($base = 0; ; $base += $inc) {
foreach($array as $rem) {
if ($base + $rem > $final) break 2;
$pattern []= $base + $rem;
}
}
Alternatively,
$i = $v = 0;
while ($v < $final) {
$v = $pattern []= $pattern[$i++] + $inc;
}
(This assumes $final will be part of the pattern.)

Answer 6

If you can figure out how to calculate the number of elements will be in the array beforehand and assign that to $tum this should work.
<?php
$arr = array(0, 1, 3);
$inc = 4; // 6
$fin = 15; // 55
$num = count($arr);
$lum = 0;
$tum = 12; // 29
do
{
for($i = $lum; $i < $num; $i++)
{
$tar = $arr[$i] + $inc;
$arr[$tar] = $tar;
}
$lum = $num;
$num *= 2;
} while(end($arr) < $fin);
$arr = array_slice($arr, 0, $tum);
print_r($arr);
echo "\n";
?>