php - how to add two associative arrays to the same array key - php

Question

I want to add two associative arrays to the same array key or take out only from the array the keys I need like the example below, the keys I need in the fields array $field = [a,b];.
Lets say I have the blow array:
array1 = Array
(
[key1] => Array
(
[a] => a
[b] => b
[c] => c
)
[key2] => Array
(
[a] => a
[b] => b
[c] => c
)
)
$field = [a,b];
$x = [];
foreach ($array1 as $key) {
foreach ($fields as $field) {
$x[$key['id']] = array($field => $key[$field]);
}
}
print_r($x);
output:
Array
(
[key1] => Array
(
[b] => b
)
[key2] => Array
(
[b] => b
)
)
I need:
Array
(
[key1] => Array
(
[a] => a
[b] => b
)
[key2] => Array
(
[a] => a
[b] => b
)
)

Answer 1

Basically you are assigning a new array everytime, what you need to do is the below code where in you are only assigning the new index and not the array.
<?php $array1 = array(
'key1' => array
(
'a' => "a",
'b' => "b",
'c' => "c"
),
'key2' => array
(
'a' => "a",
'b' => "b",
'c' => "c"
)
);
$fields = array('a','b');
$x = [];
foreach ($array1 as $key => $value) {
foreach ($fields as $field) {
if(array_key_exists($field,$array1[$key]))
$x[$key][$field] = $value[$field];
}
}
print_r($x);

Answer 2

<?php
$arr = array(
'key1'=>array('a'=>'a','b'=>'b','c'=>'c'),
'key2'=>array('a'=>'a','b'=>'b','c'=>'c'),
'key3'=>array('c'=>'c')
);
$include = array('a','b');
foreach($arr as &$res)
{
$res = array_filter($res, function($key) use ($include) {
return in_array($key, $include);
}, ARRAY_FILTER_USE_KEY);
}
unset($res);
print_r($arr);
?>
Test Results
[akshay#localhost tmp]$ php test.php
Array
(
[key1] => Array
(
[a] => a
[b] => b
)
[key2] => Array
(
[a] => a
[b] => b
)
[key3] => Array
(
)
)

Answer 3

You can do like this, by reconstruct another multidimensional with only keys that are in $field array.
Here is the code :
$field = array('a','b');
$x = array();
foreach ($array1 as $k => $key) {
foreach ($fields as $k2 => $field) {
if(in_array($k2, $field))
$x[$k][$k2] = $field;
}
}
print_r($x);