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Posted by Daz on 05/07/07 15:18
On May 7, 4:05 pm, 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!
Is there any guarantee that the arrays will all be the same length as
one-another? Are they always a set length, or can the lengths vary?
Personally, I would start with making an empty array, which is the
same length as the size of the longest array. Set all values in that
array to 0. Then, loop through each array, and loop through the values
of each array, and add them to the starting array. Now return the
array you just created. Hope that makes sense. Example to follow.
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