PHP, how to convert indexed array to associative array easily [duplicate] - php

Question

This question already has an answer here:
Convert value from specific multidimensional array key into key in new array with original arrays as value
(1 answer)
Closed 5 months ago.
What's the easiest way to convert
$a = array(
array("id" => 1, "name" => "a1"),
array("id" => 2, "name" => "a2")
);
to
$b = array(
"a1" => array("id" => 1, "name" => "a1"),
"a2" => array("id" => 2, "name" => "a2")
);
I was expecting PHP have some functional programming facilities to do something like:
$b = map($a, function($item) {
return $item["name"];
});
But I didn't find one.

Answer 1

You can use PHP array_column() function. For your use case, the second argument should be null to return the full array.
$a = array(
array("id" => 1, "name" => "a1"),
array("id" => 2, "name" => "a2")
);
$b = array_column($a, null, 'name');
and print_r($b) will result in
Array
(
[a1] => Array
(
[id] => 1
[name] => a1
)
[a2] => Array
(
[id] => 2
[name] => a2
)
)

Answer 2

The only solution I see is to loop through the array and create a new array manually.
For example, like this:
$new_array = [];
foreach ($array as $value)
$new_array[$value['name']] = $value;

Answer 3

You can simply do this
$input = [
["id" => 1, "name" => "a1"],
["id" => 2, "name" => "a2"]
];
$result = array_merge(
...array_map(
fn($item) => [$item['name'] => $item],
$input
)
);

Answer 4

Poor me need to implement this in PHP 5.2, and I do not want to use for loop
here's my implementation:
function getField($x) { return $x['name']; }
$ids = array_map('getField', $result);
$result = array_combine($ids, $result);
See if maybe this helps anybody lol

Answer 5

The accepted answer is close, but "close" only counts with hand grenades.
($unique is an indexed array)
$sub_key = 'country';
$new_array = [];
foreach ($unique as $value) {
$new_array[] = [$sub_key => $value];
}

Answer 6

How about:
$a = array(
array('a' => 'a0', 'b' => 'b0', 'c' => 'c0'),
array('a' => 'a1', 'b' => 'b1', 'c' => 'c1'),
array('a' => 'a2', 'b' => 'b2', 'c' => 'c2'),
);
print_r($a);
print_r(array_combine(array_column($a, 'a'), $a));
Where 'a' is the column to use as the associative index.
This leaves the column that becomes the index in the array.
array_column (PHP 5 >= 5.5.0, PHP 7)
array_combine (PHP 5, PHP 7)