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Posted by ZeldorBlat on 05/07/07 15:32
On May 7, 11:05 am, dennis.spreng...@gmail.com wrote:
> Consider the following multi-dimensional array:
> ---------------------------
> $arr = array(
> array(3, 5, 7, 9),
> array(2, 4, 6, 8),
> array(1, 3, 5, 7)
> );
>
> function add_arrays($arr) {
> for ($row = 0; $row < count($arr[0]); $row++) {
> for ($column = 0; $column < count($arr[$column]); $column++) {
> $totals[$row] = $totals[$row] + $arr[$column][$row];
> }
> }
> print_r($totals);
>
> }
>
> add_arrays($arr);
> ---------------------------
> This returns the following array:
> Array ( [0] => 6 [1] => 12 [2] => 18 [3] => 24 )
>
> These are the totals of the array's in $arr: 6 (3 + 2 + 1, added all
> first elements), 12 (5 + 4 + 3, added all second elements), etc. This
> took me quite a portion of the day to construct ;) However, I would
> like add_arrays to return a multidimensional array like this:
>
> Array (
> Array ( [0] => 3 [1] => 5 [2] => 7 [3] => 9 ) // 1st row
> Array ( [0] => 5 [1] => 9 [2] => 13 [3] => 17 ) // 1st row + second
> row (i.e. 5 = 3 + 2)
> Array ( [0] => 6 [1] => 12 [2] => 18 [3] => 24 ) // 1st _ 2nd + 3rd
> row (i.e. 6 = 3 + 2 + 1)
> )
>
> Could somebody please help me building a function that does just that?
> Adding one row to the previous one and adding the result to the output
> array? Any help would be greatly apprectiated!
Here's one way. Obviously there are others, also.
function add_arrays_cumulative($arr) {
$out = array();
for($i = 0; $i < count($arr); $i++) {
if(!isset($out[$i]))
$out[$i] = array();
for($j = 0; $j < count($arr[$i]); $j++)
$out[$i][$j] = $arr[$i][$j] + (isset($out[$i-1][$j]) ?
$out[$i-1][$j] : 0);
}
return $out;
}
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