Subtracting many arrays - php

Question

I have one big array circa 50 values like this (for example I used smaller array):
Array
(
[Adam Małysz] => 1
[Justyna Kowalczyk] => 2
[Janne Ahonen] => 3
[Stefan Hula] => 4
[Ole Einar Bjoerdalen] => 5
[Jakub Janda] => 6
[Mariusz Pudzianowski] => 7
[Harry Potter] => 8
[Vladimir Zografski] => 9
[Pavel Karelin] => 10
[Eddie Edwards] => 11
[Apoloniusz Tajner] => 12
)
and I have n smaller constant arrays with different values:
Array
(
[Adam Małysz] => 1
[Janne Ahonen] => 2
[Stefan Hula] => 3
[Ole Einar Bjoerdalen] => 4
[Vladimir Zografski] => 5
[Pavel Karelin] => 6
[Apoloniusz Tajner] => 7
[Mariusz Pudzianowski] => 8
[Jakub Janda] => 9
[Harry Potter] => 10
)
Array
(
[Justyna Kowalczyk] => 1
[Apoloniusz Tajner] => 2
[Harry Potter] => 3
[Janne Ahonen] => 4
[Mariusz Pudzianowski] => 5
[Adam Małysz] => 6
[Jakub Janda] => 7
[Ole Einar Bjoerdalen] => 8
[Vladimir Zografski] => 9
[Pavel Karelin] => 10
)
Array
(
[Adam Małysz] => 1
[Janne Ahonen] => 2
[Jakub Janda] => 3
[Stefan Hula] => 4
[Ole Einar Bjoerdalen] => 5
[Justyna Kowalczyk] => 6
[Harry Potter] => 7
[Mariusz Pudzianowski] => 8
[Vladimir Zografski] => 9
[Apoloniusz Tajner] => 10
)
So I want to subtract array values where is the same key like:
Big Array: [Harry Potter] => 8
[Mariusz Pudzianowski] => 7
Small Array #1: [Harry Potter] => 10
[Mariusz Pudzianowski] => 8
Small Array #2: [Harry Potter] => 3
[Mariusz Pudzianowski] => 5
Output: Difference between Small Array #1 and Big Array for key [Harry
Potter] = 2
Difference between Small Array #1 and Big Array for key [Mariusz Pudzianowski] = 1
Output: Difference between Small Array #2
and Big Array for key [Harry Potter] = 5
Difference between Small Array #2 and Big Array for key [Mariusz Pudzianowski] = 2
Basically I'm stuck.
Please help.

Answer 1

lets name your big array as $bigArray and small array as $smallArray both having key-value pair. Now the code should be:
foreach($bigArray as $bigKey=>$bigValue){
foreach($smallArray as $smallKey=>$smallValue){
if($smallKey==$bigKey){
$output=$bigValue-$smallValue;
echo 'Difference between Small Array #1 and Big Array for $bigKey is '.$output;
}
}
}
This way for every element of your big Array , you will loop small array and check if the keys are matching and if they do then you subtract their values and print them. You can do this for other small arrays as well.

Answer 2

You could use array_intersect_key to find all the key that are common to all arrays.
$commonKeys = array_intersect_key($bigArray, $smallArray1, $smallArray2, ...)
From there you just have to iterate over $commonKeys and make the appropriate substractions. Something like :
foreach ($commonKeys as $key) {
$result = abs($bigArray[$key] - $smallArray1[$key]);
echo " Difference between Small Array #1 and Big Array for key [$key] = $result";
//you do that for each Small Array
}