laravel collection mapwithkeys

1// The array we're going to return
2    $data = [];    
3// Query the users table
4$query = users::where('id', 1)->get();
5
6// Let's Map the results from [$query]
7$map = $query->map(
8    function($items){
9          $data['user_firstName'] = $items->firstName;
10          $data['user_lastName'] = $items->lastName;
11          return $data;
12        }
13    );
14
15return $map;

1$collection = collect([
2    [
3        'name' => 'John',
4        'department' => 'Sales',
5        'email' => 'john@example.com'
6    ],
7    [
8        'name' => 'Jane',
9        'department' => 'Marketing',
10        'email' => 'jane@example.com'
11    ]
12]);
13
14$keyed = $collection->mapWithKeys(function ($item) {
15    return [$item['email'] => $item['name']];
16});
17
18$keyed->all();
19
20/*
21    [
22        'john@example.com' => 'John',
23        'jane@example.com' => 'Jane',
24    ]
25*/