PHP Basics about problem two-dimensional array summation

PHP basic problem two-dimensional array summation!

Array:

$a = Array (Array ("A" => "AA", "A1" =>1, "A2" =>1), Array ("a" => "BB", "A1" =>2, "A2" =>2), Array ("a" => cc "," A1 "=>3," A2 "=>3),

Array ("A" => "AA", "A1" =>1, "A2" =>1), Array ("a" => "BB", "A1" =>5, "A2" =>5))

Sum of elements with the same first key value

Results

$r = Array (Array ("A" => "AA", "A1" =>2, "A2" =>2), Array ("a" => "BB", "A1" =>7, "A2" =>7), Array ("a" => cc "," A1 "=>3," A2 "=>3));

------Solution--------------------

$a = Array (

Array ("A" => "AA", "A1" => 1, "A2" => 1),

Array ("a" => "BB", "A1" => 2, "A2" => 2),

Array ("A" => "CC", "A1" => 3, "A2" => 3),

Array ("A" => "AA", "A1" => 1, "A2" => 1),

Array ("a" => "BB", "A1" => 5, "A2" => 5),

);

$res = Array ();

foreach ($a as $r) {

if (! isset ($res [$r [' a ']]) $res [$r [' a ']] = $r;

else {

$res [$r [' A ']][' A1 '] + + = $r [' A1 '];

$res [$r [' A ']][' A2 '] + + = $r [' A2 '];

}

}

Print_r (Array_values ($res));

Array

(

[0] => Array

(

[A] => AA

[A1] => 2

[A2] => 2

)

[1] => Array

(

[A] => BB

[A1] => 7

[A2] => 7

)

[2] => Array

(

[A] => cc

[A1] => 3

[A2] => 3

)

)