laravel collection filter

1$collection = collect([1, 2, 3, 4]);
2
3$filtered = $collection->filter(function ($value, $key) {
4    return $value > 2;
5});
6
7$filtered->all();
8
9// [3, 4]

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$itemCollection = collect($contacts);
2$filtered = $itemCollection->filter(function($item) use ($search) {
3    return stripos($item['username'],$search) !== false;
4});
5

1$collection = collect([1, 2, 3]);
2
3$total = $collection->reduce(function ($carry, $item) {
4    return $carry + $item;
5});
6
7// 6
8
9$total = $collection->reduce(function ($carry, $item) {
10    return $carry + $item;
11}, 4);
12
13// 10   | where 4 is a initial value

1$collection = collect([1,2,3,4]);
2
3$collection->each(function($item){
4    return $item*$item;
5});
6
7// [1,4,9,16]

1public function index()
2{
3    $myStudents = [
4        ['id'=>1, 'name'=>'Hardik', 'mark' => 80],
5        ['id'=>2, 'name'=>'Paresh', 'mark' => 20],
6        ['id'=>3, 'name'=>'Akash', 'mark' => 34],
7        ['id'=>4, 'name'=>'Sagar', 'mark' => 45],
8    ];
9  
10    $myStudents = collect($myStudents);
11   
12    $passedstudents = $myStudents->filter(function ($value, $key) {
13        return data_get($value, 'mark') > 34;
14    });
15   
16    $passedstudents = $passedstudents->all();
17   
18    dd($passedstudents);
19}