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Posted by Rami Elomaa on 05/07/07 17:21
ZeldorBlat kirjoitti:
> 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); $i++) {
This is hair-splitting, but since count($arr) is static, it would save
some cpu cycles to store it in a variable instead of calling count() on
each iteration:
for($i = 0, $limit=count($arr); $i < $limit ; $i++) {
Or better yet, iterate the array with foreach:
foreach($arr as $i => $row) {
> if(!isset($out[$i]))
> $out[$i] = array();
>
> for($j = 0; $j < count($arr[$i]); $j++)
Same goes here.
I've gotten so used to foreach that I'm missing it a lot when I'm using
a language that hasn't got such a structure... It's so convinient.
--
Rami.Elomaa@gmail.com
"Wikipedia on vähän niinq internetin raamattu, kukaan ei pohjimmiltaan
usko siihen ja kukaan ei tiedä mikä pitää paikkansa." -- z00ze
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