How to use array values as keys without loops? [duplicate] - php

Question

This question already has answers here:
Generate an associative array from an array of rows using one column as keys and another column as values
(3 answers)
Closed 7 months ago.
Looping is time consuming, we all know that. That's exactly something I'm trying to avoid, even though it's on a small scale. Every bit helps. Well, if it's unset of course :)
On to the issue
I've got an array:
array(3) {
'0' => array(2) {
'id' => 1234,
'name' => 'blablabla',
},
'1' => array(2) {
'id' => 1235,
'name' => 'ababkjkj',
},
'2' => array(2) {
'id' => 1236,
'name' => 'xyzxyzxyz',
},
}
What I'm trying to do is to convert this array as follows:
array(3) {
'1234' => 'blablabla',
'1235' => 'asdkjrker',
'1236' => 'xyzxyzxyz',
}
I guess this aint a hard thing to do but my mind is busted right now and I can't think of anything except for looping to get this done.

Answer 1

Simply use array_combine along with the array_column as
array_combine(array_column($array,'id'), array_column($array,'name'));
Or you can simply use array_walk if you have PHP < 5.5 as
$result = array();
array_walk($array, function($v)use(&$result) {
$result[$v['id']] = $v['name'];
});
Edited:
For future user who has PHP > 5.5 can simply use array_column as
array_column($array,'name','id');
Fiddle(array_walk)

Answer 2

UPD: Warning the slowest solution! See benchmarks below.
Try this code:
$a = array(array('id' => 1234,
'name' => 'blablabla'),
array('id' => 1235,
'name' => 'ababkjkj'),
array('id' => 1236,
'name' => 'xyzxyzxyz'));
var_export(array_reduce($a, function($res, $item) {
$res[$item['id']] = $item['name'];
return $res;
}));
Works fine even in PHP 5.3. And uses only one function array_reduce.
UPD:
Here are some benchmarks (PHP 5.6 over Debian 7 on a medium quality server):
$a = [];
for ($i = 0; $i < 150000; $i++) {
$a[$i] = ['id' => $i,
'name' => str_shuffle('abcde') . str_shuffle('01234')];
}
$start = microtime(true);
if (false) {
// 7.7489550113678 secs for 15 000 itmes
$r = array_reduce($a, function($res, $item) {
$res[$item['id']] = $item['name'];
return $res;
});
}
if (false) {
// 0.096649885177612 secs for 150 000 items
$r = array_combine(array_column($a, 'id'),
array_column($a, 'name'));
}
if (true) {
// 0.066264867782593 secs for 150 000 items
$r = [];
foreach ($a as $subarray) {
$r[$subarray['id']] = $subarray['name'];
}
}
if (false) {
// 0.32427287101746 secs for 150 000 items
$r = [];
array_walk($a, function($v) use (&$r) {
$r[$v['id']] = $v['name'];
});
}
echo (microtime(true) - $start) . ' secs' . PHP_EOL;
So, as a conclusion: plain iteration with simple for loop is a winner (as mentioned in this answer). On a second place there is array_combine allowed only for new versions of PHP. And the worst case is using my own solution with closure and array_reduce.

Answer 3

If you have php >= 5.5:
$res = array_combine(array_column($source, 'id'), array_column($source, 'name'));
If not - make a loop.

Answer 4

Make use of array_map function, (PHP 4 >= 4.0.6, PHP 5)
[akshay#localhost tmp]$ cat test.php
<?php
$array = array(
array('id' => 1234,'name' => 'blablabla'),
array('id' => 1235,'name' => 'ababkjkj'),
array('id' => 1236,'name' => 'xyzxyzxyz')
);
$output = array();
array_map(function($_) use (&$output){ $output[$_['id']] = $_['name']; },$array);
// Input
print_r($array);
// Output
print_r($output);
?>
Output
[akshay#localhost tmp]$ php test.php
Array
(
[0] => Array
(
[id] => 1234
[name] => blablabla
)
[1] => Array
(
[id] => 1235
[name] => ababkjkj
)
[2] => Array
(
[id] => 1236
[name] => xyzxyzxyz
)
)
Array
(
[1234] => blablabla
[1235] => ababkjkj
[1236] => xyzxyzxyz
)

Answer 5

This is the fastest and simplest code here so far ...
$result = [];
foreach ($input as $subarray) {
$result[$subarray["id"]] = $subarray["name"];
}

Answer 6

Try this function:
array_combine(array_column($array,'id'), array_column($array,'name'));