Extract array parts based on given keys in array - php

Question

I have two arrays. One containing the data and other contains the keys. So I have
$data = array(
'name' => array('label' => 'Name:', 'value' => 'Genghis'),
'age' => array('label' => 'Age:', 'value' => '67'),
'weigh' => array('label' => 'Weigh in Kgs:', 'value' => '78')
);
and
$keys = array('name', 'age');
Now I want to extract only the name and age elements of $data. Some thing like this.
$extracted = somemethod($data, $keys);
var_export($extracted);
Output should be like this.
array(
'name' => array(
'label' => 'Name:',
'value' => 'Genghis',
),
'age' => array(
'label' => 'Age:',
'value' => '67',
),
)
How can i do this?

Answer 1

I would use an array_intersect_key() function like this:
$data = array(...); // initial array as described
$retained_keys = array('name' => 'value not used', 'age' => 'value not used');
$filtered_array = array_intersect_key($data, $retained_keys);

Answer 2

Loop over the keys, grab the array values, and return them:
function somemethod($data, $keys) {
$return = array();
foreach( $keys as $k) {
$return[$k] = isset( $data[$k]) ? $data[$k] : null;
}
return $return;
}
The above adds 'null' when a field isn't found. You can modify the foreach loop to just skip the key when it's not found in the $data array, like this:
function somemethod($data, $keys) {
$return = array();
foreach( $keys as $k) {
if( isset( $data[$k])) {
$return[$k] = $data[$k];
}
}
return $return;
}
Edit: To extend on Mike Brant's answer, array_intersect_key() can be used with array_flip() in a function to achieve the desired output:
function somemethod($data, $keys) {
$keys = array_flip( $keys);
return array_intersect_key($data, $keys);
}
Yes, it uses array_flip(), but the original $keys array is left unmodified, as a copy of that array is what gets flipped. So, you would still call this function with:
$extracted = somemethod( $data, array('name', 'age'));

Answer 3

Not exactly onerous to write
$extracted = array();
foreach($keys as $key) {
if (isset($data[$key]))
$extracted[$key] = $data[$key];
}