PHP Group array by date

I have the following array that gathers data from purchases, visits and coupons generated in my application:

    array:10 [
      0 => array:2 [
        "dt" => "2020-11-18"
        "cupoms" => 9
      ]
      1 => array:2 [
        "dt" => "2020-11-19"
        "cupoms" => 1
      ]
      2 => {#1421 
        +"dt": "2020-11-14"
        +"visits": 1
      }
      3 => {#1423 
        +"dt": "2020-11-15"
        +"visits": 1
      }
      4 => {#860 
        +"dt": "2020-11-16"
        +"visits": 9
      }
      5 => {#530 
        +"dt": "2020-11-18"
        +"visits": 48
      }
      6 => {#1527 
        +"dt": "2020-11-19"
        +"visits": 3
      }
      7 => array:2 [
        "dt" => "2020-11-15"
        "orders" => 1
      ]
      8 => array:2 [
        "dt" => "2020-11-17"
        "orders" => 3
      ]
      9 => array:2 [
        "dt" => "2020-11-19"
        "orders" => 4
      ]
    ]

I need to group it by date (more specifically the ‘dt’ field), so that the data is like as follows:

    "dt" => "2020-11-18"
    "cupoms" => 9
    "visits"=> 48
    
    "dt" => "2020-11-19"
    "cupoms" => 1
    "visits" => 3
    "orders" => 4
    
    "dt" => "2020-11-14"
    "visits"=> 1

I tried a few loops, but to no avail

Answer

Update: I edited the answer because I realized that it wasn’t adding the numerical values together, it was just taking the first value; The code got a bit more complicated but there is no straightforward way to do it with collections, I’d sill recommend using collections instead of loops of arrays

---

With laravel you can take advantage of collections, they are very powerfull, here is a working example:

        $array = [
      [
        "dt" => "2020-11-18",
        "cupoms" => 9
      ],
      [
        "dt" => "2020-11-19",
        "cupoms" => 1
      ],
      [
        "dt"=> "2020-11-14",
        "visits"=> 1
      ],
      [
        "dt"=> "2020-11-15",
        "visits"=> 1
      ],
      [
        "dt"=> "2020-11-16",
        "visits"=> 9
      ],
      [
        "dt"=> "2020-11-18",
        "visits"=> 48
      ],
      [
        "dt"=> "2020-11-19",
        "visits"=> 3
      ],
      [
        "dt" => "2020-11-15",
        "orders" => 1
      ],
      [
        "dt" => "2020-11-17",
        "orders" => 3
      ],
      [
        "dt" => "2020-11-19",
        "orders" => 4
      ]
    ];

    $collection = collect($array);

    $grouped = $collection->groupBy('dt');

    //up to this step($merged_rec) you already preserved and grouped all the values 
    //and you can sum the values manually if you wish, 
    //but in the next step I will suggest a solution using collections
    $merged_rec = $grouped->map(function ($items) {
        return collect($items)->reduce(function ($carry, $item) {
            return collect($carry)->mergeRecursive($item);
        }, collect([]));
    });
    
    //this will reduce the numeric arrays to a single value (sum) 
    //using collections
    $summed = $merged_rec->map(function ($items){
        return collect($items->map(function($subitems) {
            if( is_array($subitems) && count($subitems) > 0 && is_numeric($subitems[0]) ){
                return collect($subitems)->sum();
            } else {
                return $subitems;
            }
        }));
    });

    print_r($summed->toArray());

this will output:

    array:6 [
      "2020-11-18" => array:3 [
        "dt" => array:2 [
          0 => "2020-11-18"
          1 => "2020-11-18"
        ]
        "cupoms" => 9
        "visits" => 48
      ]
      "2020-11-19" => array:3 [
        "dt" => array:3 [
          0 => "2020-11-19"
          1 => "2020-11-19"
          2 => "2020-11-19"
        ]
        "cupoms" => 1
        "visits" => 3
      ]
      "2020-11-14" => array:2 [
        "dt" => "2020-11-14"
        "visits" => 1
      ]
      "2020-11-15" => array:3 [
        "dt" => array:2 [
          0 => "2020-11-15"
          1 => "2020-11-15"
        ]
        "visits" => 1
        "orders" => 1
      ]
      "2020-11-16" => array:2 [
        "dt" => "2020-11-16"
        "visits" => 9
      ]
      "2020-11-17" => array:2 [
        "dt" => "2020-11-17"
        "orders" => 3
      ]
    ]

Read more: https://laravel.com/docs/8.x/collections#method-groupby