Change array keys according to another one

Question

I have 2 arrays:

$array1 = array(1 => "aaa", 4 => "bbb", 5 => "ccc", 8 => "ddd", 9 => "eee", 11 => "fff");
$array2 = array(2 => "", 3 => "", 6 => "", 7 => "", 9 => "", 13 => "");

I want to change the keys of $array1 according to $array2. I'm given the information that an element of the second array has to correspond to another of the first one. For example I know that $array2[6] has to correspond to $array1[4].

So I should have all the keys of $array1 changed according to this rule:

$array1 = array(3 => "aaa", 6 => "bbb", 7 => "ccc", 9 => "ddd", 13 => "eee", 2 => "fff");

I don't know how to solve this. I've tried to split the first array where the element given is but I'm stuck.

How can you tell that '$array2[6] has to correspond to $array1[4]' ? — Vatev
– Vatev, Commented Jul 29, 2012 at 17:30
@Vatev I know that from another function, but basically that input could vary from time to time, I should be able to change the keys of the first array in every occurrence (it could be array2[13] has to correspond to $array1[9] or whatever). Note that both arrays have the same number of elements. — Giorgio
– Giorgio, Commented Jul 29, 2012 at 17:39
This doesn't make sense because you haven't told us the pattern. — Raiden
– Raiden, Commented Jul 29, 2012 at 17:39
@Raiden I bet it's my poor English :) However given the starting point: eg $a2[6] = $a1[4], all the other elements of the first array should be set according to that with the keys taken from the second array — Giorgio
– Giorgio, Commented Jul 29, 2012 at 17:41

pyrospade · Accepted Answer · 2012-07-30 02:42:34Z

1

You can define a function that maps and constructs a new array.

function transfer_keys($key_array,
                       $value_array) {
    $a = array_map(null, array_keys($key_array),
                   $value_array);
    $result = array();
    foreach($a as $kv) {
        $result[$kv[0]] = $kv[1];
    }
    return $result;
}

$array1 = array(1 => "aaa", 4 => "bbb", 5 => "ccc", 
                8 => "ddd", 9 => "eee", 11 => "fff"); 
$array2 = array(2 => "", 3 => "", 6 => "", 7 => "", 
                9 => "", 13 => "");    

print_r(transfer_keys($array2, $array1));

edited Jul 30, 2012 at 2:42

answered Jul 29, 2012 at 18:24

pyrospade

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Comments

Jerska · Accepted Answer · 2012-07-29 17:59:17Z

if you wanna update all elements of your first array with the values in the array2 in the same order :

$i = 0;
foreach ($array1 as $v) {
    while (!isset($array2[$v]))
        $i++;
    $array2[$i] = $v;
}

But if you want to update according to an order you pre-defined, you have to make something else, like a table defining the rule :

$assoc_array = array(
    2 => 4,
    3 => 7,
    4 => 11,
    6 => 5,
    5 => 9,
    8 => 1);
foreach ($assoc_array as $k => $v) {
    $array1[$k] = $array2[$v];
}

Hope this helps.

Aw, you know the difference is always the same !

Then this should be something like :

function updateArray ($array1, $array2, $key_of_array1, $key_associated_of_array2) {
    $diff = $key_associated_of_array2 - $key_of_array1;
    foreach ($array1 as $k => $v) {
        $array2[$k + $diff] = $array1[$k];
    } 
}

Hardik · Accepted Answer · 2012-07-29 17:41:01Z

0

you can get first keys of both arrays using function array_keys();

suppose, $keys1 contains keys of $array1 and $keys2 cotains keys of $array2

Then move into for loop as follows:

for($i=0 ; $i<count($array1) ; $i++)
{
    $result[$keys2[$i+1]] = $array1[$i];
}

print_r($result);

Hope this will be helpful to you

answered Jul 29, 2012 at 17:41

Hardik

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Comments

Raiden · Accepted Answer · 2012-07-29 17:47:41Z

0

foreach($array1 as $item => $value)
 if(isset($array2[($item + 2)]) && item != 11)
  $temp[$item + 2] = $value;
 elseif($item == 11)
  $temp[2] = $value;
$array1 = @$temp;

Example code.. but again, you need to tell us the pattern that determines where the first array elements are being inserted into the second array elements. I think it's.. +2? Maybe?

edited Jul 29, 2012 at 17:47

answered Jul 29, 2012 at 17:41

Raiden

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2 Comments

Giorgio Over a year ago

There is no pattern between the keys of each array. BUT the distance between two elements of the same array is always the same. EG $a1 --> 1 3 4 7 11 $a2 --> 70 73 74 77 81

Giorgio Over a year ago

If I know that 73-->11 I'll change the numbers in the first array to $a1 --> 74 77 81 70 73

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