Combine and transpose three arrays with associative keys

Question

I have three arrays for instance

Array1
array (size=3)
0 => string 'a' (length=1)
1 => string 'b' (length=1)
2 => string 'c' (length=1)

Array2
array (size 3)
0 => string '$' (length=1)
1 => string '%' (length=1)
2 => string '^' (length=1)

Array3
array (size 3)
0 => int '1' (length=1)
1 => int '2' (length=1)
2 => int '3' (length=1)

I want an array4 to be have this configuration that each array's each row should be one group. For instance

Array4
0th 
name=a
type=$
price=1

1st
name=b
type=%
price=2

2nd
name=c
type=^
price=3

I tried this and gave me perfect result

$output = array_combine($array1, $array2);

But when I tried this it wouldn't give expected result

$output = array_combine(array_combine($array, $array2),$array3);

Answer 1

utilizing functional helpers

By using array_map and array_combine, you can skip having to handle things like counts, iterators, manual array assignment, and manual array combining.

This solution reduces complexity by using procedures which hide all that complexity behind useful, functional APIs.

$names = ['a', 'b', 'c'];
$types = ['$', '%', '^'];
$prices = [1, 2, 3];

$result = array_map(function ($name, $type, $price) {
  return array_combine(
    ['name', 'type', 'price'],
    [$name, $type, $price]
  );
}, $names, $types, $prices);

echo json_encode($result, JSON_PRETTY_PRINT);

Output (some line-breaks removed for brevity)

[
  {"name": "a", "type": "$", "price": 1},
  {"name": "b", "type": "%", "price": 2},
  {"name": "c", "type": "^", "price": 3}
]

---

hiding your own complexity

You can even abstract away your own complexity by defining your own procedure, array_zip_combine — which works like array_combine but accepts multiple input arrays which are first "zipped" before being combined

this solution requires PHP 7+

// PHP 7 offers rest parameter and splat operator to easily apply variadic function
function array_zip_combine (array $keys, ...$arrs) {
  return array_map(function (...$values) use ($keys) {
    return array_combine($keys, $values);
  }, ...$arrs);
}

$result = array_zip_combine(['name', 'type', 'price'], $names, $types, $prices);

same solution for PHP 5.4+

// PHP 5 doesn't offer splat operator so we have to use
// call_user_func_array to apply a variadic function
function array_zip_combine (array $keys /* args */) {
  $f = function () use ($keys) { return array_combine($keys, func_get_args()); };
  return call_user_func_array(
    'array_map',
    array_merge([$f], array_slice(func_get_args(), 1))
  );
}

$result = array_zip_combine(['name', 'type', 'price'], $names, $types, $prices);

Answer 2

Simple solution using array_map and array_combine functions:

$result = array_map(function($item) {
    return array_combine(['name', 'type', 'price'], $item);
}, array_map(null, $array1, $array2, $array3));

print_r($result);

The output:

Array
(
    [0] => Array
        (
            [name] => a
            [type] => $
            [price] => 1
        )

    [1] => Array
        (
            [name] => b
            [type] => %
            [price] => 2
        )

    [2] => Array
        (
            [name] => c
            [type] => ^
            [price] => 3
        )
)

Answer 3

If you know that all three arrays are the same length and have all required data, a simple fix would be to iterate over that length and build your results array:

$result = []; 
$count = count($array1);
for($i=0; $i < $count; $i++){
    $result[$i] = [
        'name'=>$array1[$i],
        'type'=>$array2[$i],
        'price'=>$array3[$i]
    ];
}

$result holds what you need. What you're trying -- array_combined() -- is not made to build one array with values from the others so it won't work for this purpose. That function is to build an array whose keys come from one array and values from another.