Group and sum Laravel collection data by date value of a datetime column

I have a variable called $data which holds a collection that looks something like this:

[
    "date" => "2017-10-07 10:00:00"
    "usage" => 0.423
    "costs" => 1.212
],
[
    "date" => "2017-10-07 11:00:00"
    "usage" => 0.786
    "costs" => 1.564
],
[
    "date" => "2017-10-07 12:00:00"
    "usage" => 0.542
    "costs" => 1.545
]

(The data can be every hour for up to 2 months, for readability I chose to include only 3 hours in this example)

As you can see, it's all per hour (which is also data I need for a different part in the code) I would like a separate collection per day. Is there an easy way to group by date('Ymd') and sum usage and costs? I should also mention that not all items in the collection have all indexes. Some don't have usage, some don't have costs. All do have date however.

You could possibly achieve this with something like this:

$collection = collect([
    [
        "date" => "2017-10-07 10:00:00",
        "usage" => 0.423,
        "costs" => 1.212
    ],
    [
        "date" => "2017-10-07 11:00:00",
        "usage" => 0.786,
        "costs" => 1.564
    ],
    [
        "date" => "2017-10-07 12:00:00",
        "usage" => 0.542,
        "costs" => 1.545
    ],
    [
        "date" => "2017-10-08 10:00:00",
        "costs" => 1.1
    ],
    [
        "date" => "2017-10-08 11:00:00",
        "usage" => 0.786,
    ],
    [
        "date" => "2017-10-08 12:00:00",
        "costs" => 1.567
    ]
]); 


return $collection->groupBy(function($row) {
    return Carbon\Carbon::parse($row['date'])->format('Y-m-d'); 
})->map(function($value, $key) {
    return [
        'usage' => $value->sum('usage'), 
        'costs' => $value->sum('costs')
    ];
});

The output of the above will be this:

Collection {#267 ▼
  #items: array:2 [▼
    "2017-10-07" => array:2 [▶]
    "2017-10-08" => array:2 [▼
      "usage" => 0.786
      "costs" => 2.667
    ]
  ]
}

As you can see from the above, some of the items do not have usage or costs. It will still work.

Here's also an example you can play with.