Is there a function to extract a 'column' from an array in PHP?

Question

I have an array of arrays, with the following structure :

array(array(\'page\' => \'page1\', \'name\' => \'pagename1\')
      array(\'page\' => \'pa         


        

Answer 1

Similar to fuentesjrs solution, but a bit more generic using array_walk() with a custom callback:

// Define the callback
function extract_named_sub_elements(&$item, $key, $name) {
  $item = $item[$name];
}

// Test data
$original = array(
  array('page' => 'page1', 'name' => 'pagename1'),
  array('page' => 'page2', 'name' => 'pagename2'),
  array('page' => 'page3', 'name' => 'pagename3'),
);

// Use a copy, as array_walk() operates directly on the passed in array
$copy = $original;

// Substitute 'name' with whatever element you want to extract, e.g. 'page'
array_walk($copy, 'extract_named_sub_elements', 'name');

print_r($copy);

Answer 2

Yes, there is a php built-in function called array_column which does what you are looking for.

You would call it something like $name_keys = array_column($array, 'name'); to get the result that you are looking for.

Please refer to the following entry in the PHP manual for more details:

http://php.net/manual/en/function.array-column.php

Answer 3

I don't think there is any need to have a built in function for this. There may be an array in your those array.

$samples=array(
            array('page' => 'page1', 'name' => 'pagename1'),
            array('page' => 'page2', 'name' => 'pagename2'),
            array('page' => 'page3', 'name' => 'pagename3')
            );

$output1=array();
$output2=array();
foreach($samples as $sample){
    array_push($output1,$sample['name']);
    $output2[]=array_splice($sample,1);

}

print_r($output1);
print_r($output2);

in $output1 is the output what you want if you want only to remove the 'page' indexing' part then $output2.

if you need all the values from the that array and indexes numerically the array then you can use

$array_1=array_values($samples); 

but what i understand, you didn't want this.

Answer 4

With array_reduce:

$names = array_reduce($array, function ($carry, $item) {
    return array_merge($carry, [$item['name']]);
}, []);

Answer 5

Here's a functional way of doing it:

$data = array(
            array('page' => 'page1', 'name' => 'pagename1'),
            array('page' => 'page2', 'name' => 'pagename2'),
            array('page' => 'page3', 'name' => 'pagename3'));

$result = array_map(create_function('$arr', 'return $arr["name"];'), $data);
print_r($result);

Answer 6

Just to extend on some of the answers here, as of PHP 5.5, array_column is what you want.

It actually has a few possible uses.

Using the sample array below, here are the different ways to use array_column.

$a = array(
    array('id' => '1', 'name' => 'Joe'),
    array('id' => '2', 'name' => 'Jane')
);

Retrieving a single column as the array

$b = array_column($a, 'name');

Would give you. Notice the auto keys starting from 0, as per a normal array.

$b[0] = 'Joe';
$b[1] = 'Jane';

Retrieving the full array with a column as the index.

$c = array_column($a, NULL, 'id');

Would result in the following.

$c[1] = array('id' => '1', 'name' => 'Joe');
$c[2] = array('id' => '2', 'name' => 'Jane');

Notice how the column I selected as the third parameter becomes the key for each item and I get the full array by setting the second parameter to null.

Of course, the final usage is to set both the 2nd and 3rd params.

$d = array_column($a, 'name', 'id');

Would give you the following.

$d[1] = 'Joe';
$d[2] = 'Jane';

I personally use the full 3 params for creating select option lists. If I have a table with my options, I query the table and get the result and pass it into this to get a list with the key as the value and the label. This is a brilliant way for building info sets that need to intersect by the index as well.