ASP.NET Core MVC 計算 ENUM 的百分比

Question

如何計算 ENUM 的出現百分比？ 我有一個預訂清單，我的 ENUM 中有 2 種不同類型的 sockets。 例如，如果 booking_1 有 type_1，booking_2 有 type_1，然后 booking_3 有 type_2 我應該在我的視圖表中使用 type_1 66.6% 和 type_2 33.3%

這是我的枚舉：

        namespace WebApplication.Models
{
    public enum ConnectorType
    {
        [Display(Name = "Type 2-Plug")]
        Type2Plug,
        [Display(Name = "CCS Combo 2-Plug")]
        CCSCombo2Plug
    }
}

這是視圖模型：

namespace WebApplication.ViewModels
{
    public class ConnectorTypeEvaluationViewModel
    {
        [Display(Name = "Anschlusstyp")]
        public ConnectorType connectorType { get; set; }
        [Display(Name = "Prozentsatz")]
        public double connectorPercentage { get; set; }
    }
}

我的問題是 Controller。 我不知何故需要使用循環來計算我的 ENUM 類型在我的 bookingsList 中每次出現的百分比，但我不知道如何：

namespace WebApplication.Controllers
{
   public class ConnectorTypeEvaluationController : Controller
   {
       private IMemoryCache _cache;
       public ConnectorTypeEvaluationController(IMemoryCache cache)
       {
           _cache = cache;
       }
       public IActionResult Index()
       {
           List<Booking> bookingsList;
           _cache.TryGetValue("key", out bookingsList);
           double total = bookingsList.Count;
           connectorType = ??;
           connectorPercentage = ??;
           return View();
       }
   }
}

Answer 1

據我了解，您想計算所有預訂的每個連接器類型的百分比。 使用這兩個連接器創建一個列表並計算百分比如下：

List<ConnectorTypeEvaluationViewModel> connectorTypeEvaluationViewModel = new List<ConnectorTypeEvaluationViewModel>();

connectorTypeEvaluationViewModel.Add(new ConnectorTypeEvaluationViewModel
            {
                connectorType = ConnectorType.Type2Plug,
                connectorPercentage = (bookingsList.Count(s => s.connectorType==ConnectorType.Type2Plug)/Convert.ToDouble(bookingsList.Count()))*100
            });

connectorTypeEvaluationViewModel.Add(new ConnectorTypeEvaluationViewModel
            {
                connectorType = ConnectorType.CCSCombo2Plug,
                connectorPercentage = (bookingsList.Count(s => s.connectorType== ConnectorType.CCSCombo2Plug) / Convert.ToDouble(bookingsList.Count())) * 100
            });

Answer 2

百分比計算為(i / n) * 100 ，其中n是觀察總數， i是 Type2Plug 的數量。

可能會以某種方式進行優化，也許是通過使用GroupBy 。

public IActionResult Index()
{
   List<Booking> bookingsList;
   _cache.TryGetValue("key", out bookingsList);

   double type2PlugCount = bookingsList.Count(x => x.connectorType == ConnectorType.Type2Plug);
   double cCSCombo2PlugCount = bookingsList.Count(x => x.connectorType == ConnectorType.CCSCombo2Plug);
   double total = bookingsList.Count;

   var type2PlugPercentage = (type2PlugCount / total) * 100;
   var cCSCombo2PlugPercentage = (cCSCombo2PlugCount / total) * 100;

   return View();
}

編輯

我創建了一種基於屬性計算百分比的通用方法

public static Dictionary<TProperty, double> Percentage<T, TProperty>(this IEnumerable<T> source, Expression<Func<T,TProperty>> selector)
{
    var dict = new Dictionary<TProperty, double>();
    Func<T,TProperty> func = selector.Compile();

    var list = source.ToList();
    var groups = list.GroupBy(func).ToList();
    double total = list.Count;

    foreach(var group in groups)
    {
        double groupCount = group.Count();
        var percentage = (groupCount / total) * 100;
        dict.Add(group.Key, percentage);
    }

    return dict;
}

用法

var dict = list.Percentage(x => x.SomeProperty);

https://dotnetfiddle.net/Hqy9GV

Answer 3

非常感謝您的幫助。 我設法創建了一個 foreach 循環來添加每種類型，所以如果我需要更多類型，我不必手動添加所有類型：這是代碼：

namespace WebApplication.Controllers
{
    public class ConnectorTypeEvaluationController : Controller
    {
        private IMemoryCache _cache;
        public ConnectorTypeEvaluationController(IMemoryCache cache)
        {
            _cache = cache;
        }
        public IActionResult Index()
        {
            List<Booking> bookingsList;
            _cache.TryGetValue("key", out bookingsList);
            List<ConnectorTypeEvaluationViewModel> connectorsList = new List<ConnectorTypeEvaluationViewModel>();
            var connectors = Enum.GetValues(typeof(ConnectorType)).Cast<ConnectorType>();
            foreach (var item in connectors)
            {
                connectorsList.Add(new ConnectorTypeEvaluationViewModel
                {
                    connectorType = item,
                    connectorPercentage = (bookingsList.Count(s => s.connectorType == item) / Convert.ToDouble(bookingsList.Count())) * 100
                });
            }

            return View(connectorsList);
        }
    }
}