Rearrange array to code optimization [duplicate] - php

Question

I have an array of arrays, with the following structure :
array(array('page' => 'page1', 'name' => 'pagename1')
array('page' => 'page2', 'name' => 'pagename2')
array('page' => 'page3', 'name' => 'pagename3'))
Is there a built-in function that will return a new array with just the values of the 'name' keys? so I'd get:
array('pagename1', 'pagename2', 'pagename3')

Answer 1

As of PHP 5.5 you can use array_column():
<?php
$samples=array(
array('page' => 'page1', 'name' => 'pagename1'),
array('page' => 'page2', 'name' => 'pagename2'),
array('page' => 'page3', 'name' => 'pagename3')
);
$names = array_column($samples, 'name');
print_r($names);
See it in action

Answer 2

Why does it have to be a built in function? No, there is none, write your own.
Here is a nice and easy one, as opposed to others in this thread.
$namearray = array();
foreach ($array as $item) {
$namearray[] = $item['name'];
}
In some cases where the keys aren't named you could instead do something like this
$namearray = array();
foreach ($array as $key => $value) {
$namearray [] = $value;
}

Answer 3

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 4

Well there is. At least for PHP > 5.5.0 and it is called array_column
The PHP function takes an optional $index_keyparameter that - as per the PHP website - states:
$index_key
The column to use as the index/keys for the returned array. This value
may be the integer key of the column, or it may be the string key name
In the answers here, i see a stripped version without the optional parameter.
I needed it, so, here is the complete function:
if (!function_exists('array_column')) {
function array_column($array, $column, $index_key = null) {
$toret = array();
foreach ($array as $key => $value) {
if ($index_key === null){
$toret[] = $value[$column];
}else{
$toret[$value[$index_key]] = $value[$column];
}
}
return $toret;
}
}

Answer 5

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 6

if (!function_exists('array_column')) {
function array_column($array,$column) {
$col = array();
foreach ($array as $k => $v) {
$col[]=$v[$column];
}
return $col;
}
}
This should work for php versions < 5.5 and degrade in case the function exist

Answer 7

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 8

You can extend the ArrayIterator class and override the method mixed current(void).
class Foo extends ArrayIterator {
protected $index;
public function __construct($array, $index) {
parent::__construct($array);
$this->index = $index;
}
public function current() {
$c = parent::current();
return isset($c[$this->index]) ? $c[$this->index] : null;
}
}
$a = array(
array('page' => 'page1', 'name' => 'pagename1'),
array('name' => '---'),
array('page' => 'page2', 'name' => 'pagename2'),
array('page' => 'page3', 'name' => 'pagename3')
);
$f = new Foo($a, 'page');
foreach($f as $e) {
echo $e, "\n";
}
prints
page1
page2
page3

Answer 9

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 10

There is a built-in function actually, it's called array_column(...).
Here is all you need to know about it : https://www.php.net/manual/fr/function.array-column.php

Answer 11

Not a 'built-in', but short arrow functions make for abrreviated explicit coding (introduced in Php v7.4.) and can be used with array_map for array transformations.
Here applying a callback to each member of the array that returns the desired attribute from each subarray:
<?php
$data =
[
['page' => 'page1', 'name' => 'pagename1'],
['page' => 'page2', 'name' => 'pagename2'],
['page' => 'page3', 'name' => 'pagename3']
];
$names = array_map(fn($v) => $v['name'], $data);
var_export($names);
Output:
array (
0 => 'pagename1',
1 => 'pagename2',
2 => 'pagename3',
)
The OP posted this question before array_column exisited (from Php 5.5.0). This answers the original question with a short solution:
$names = array_column($data, 'name');
But a simple loop is also trite:
foreach($data as $item) $names[] = $item['name'];

Answer 12

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

Answer 13

You can get column, bind key value as well:
$a = array(
array(
'id' => 5698,
'first_name' => 'Peter',
'last_name' => 'Griffin',
),
array(
'id' => 4767,
'first_name' => 'Ben',
'last_name' => 'Smith',
),
array(
'id' => 3809,
'first_name' => 'Joe',
'last_name' => 'Doe',
)
);
if you want only column then use:
$last_names = array_column($a, 'last_name');
print_r($last_names);
if you want to bind key and values then use:
$last_names = array_column($a, 'last_name', 'id');
print_r($last_names);

Answer 14

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.

Answer 15

I wanted to post here, even if this is an old question, because it is still very relevant and many developers do not use PHP >= 5.5
Let's say you have an array like this:
Array
(
[files] => Array
(
[name] => Array
(
[0] => file 1
[1] => file 2
[2] => file 3
)
[size] => Array
(
[0] => 1
[1] => 2
[2] => 3
)
[error] => Array
(
[0] => abc
[1] => def
[2] => ghi
)
)
)
and the output you want is something like this:
Array
(
[0] => Array
(
[0] => file 1
[1] => 1
[2] => abc
)
[1] => Array
(
[0] => file 2
[1] => 2
[2] => def
)
[2] => Array
(
[0] => file 3
[1] => 3
[2] => ghi
)
)
You can simply use the array_map() method without a function name passed as the first parameter, like so:
array_map(null, $a['files']['name'], $a['files']['size'], $a['files']['error']);
Unfortunately you cannot map the keys if passing more than one array.