如何从列表中删除多个元素

Question

这是清单...

 List<Location> locations = new List<Location>();
 locations.Add(new Location("Narayana International", 28.6075582, 77.04700729999999));
 locations.Add(new Location("Digital zone", 28.8610328484855, 77.0951520020164));
 locations.Add(new Location("Vijay computers", 28.841364952771706, 77.09076910484801));
 locations.Add(new Location("Codac Info", 29.967759964202948, 76.88406425590289));
 locations.Add(new Location("Balaji computers", 30.6920753011206, 76.80162611916126));
 locations.Add(new Location("Aadi online exam solutions", 30.393033405609803, 76.79088732285474));

计算与当前位置的距离，然后找到最近的位置并在控制台上打印，然后删除该位置，再次找到最近的位置并在控制台上打印，然后删除该迭代继续直到 4 个元素被删除的位置。

现在，这是我尝试过的代码，但是如何删除多个元素..

List<Location> locations = new List<Location>();
   locations.Add(new Location("Narayana International", 28.6075582, 77.04700729999999));
   locations.Add(new Location("Digital zone", 28.8610328484855, 77.0951520020164));
   locations.Add(new Location("Vijay computers", 28.841364952771706, 77.09076910484801));
   locations.Add(new Location("Codac Info", 29.967759964202948, 76.88406425590289));
   locations.Add(new Location("Balaji computers", 30.6920753011206, 76.80162611916126));
   locations.Add(new Location("Aadi online exam solutions", 30.393033405609803, 76.79088732285474));
  
   double searchLat = 19;
   double searchLong = 74;

   Dictionary<double, List<Location>> distances = new Dictionary<double, List<Location>>();

   locations.ForEach(location =>
   {
       double distance = Program.GetDistance(location.Latitude, location.Longitude, searchLat, searchLong);
       if (distances.ContainsKey(distance))
       {
           distances[distance].Add(location);
       }
       else
       {
           distances.Add(distance, new List<Location>() { location });
       }

   });
   Console.WriteLine("Locations Are:" + locations.Count);
   Console.WriteLine(locations);
   Console.WriteLine("This is the nearest location to me:");

 
   var abc = locations.OrderBy(x => x.Place).ToList();
   double closestDistanceFromSearch = distances.Keys.OrderBy(k => k).First();
   Console.WriteLine(distances[distances.Keys.OrderBy(k => k).First()].Select(x => x.Place).ToList());

  

 locations.RemoveAt(0); // remove object at position 1, in this case 
      Console.WriteLine("Elements are remove:" );
     foreach (var a in locations)
          Console.WriteLine(a.ToString());
  Console.WriteLine("Now the count is : "+ locations.Count  );
           Console.ReadLine();

      


public static double GetDistance(double latitude, double longitude, double otherLatitude, double otherLongitude) {
    var d1 = latitude * (Math.PI / 180.0);
    var num1 = longitude * (Math.PI / 180.0);
    var d2 = otherLatitude * (Math.PI / 180.0);
    var num2 = otherLongitude * (Math.PI / 180.0) - num1;
    var d3 = Math.Pow(Math.Sin((d2 - d1) / 2.0), 2.0) + Math.Cos(d1) * Math.Cos(d2) * Math.Pow(Math.Sin(num2 / 2.0), 2.0);
   // var d3 = Math.Sqrt((Math.Pow(d1  - d2 , 2) + Math.Pow(num1 - num2, 2)));
   Console.WriteLine(d3);

  return 6376500.0 * (2.0 * Math.Atan2(Math.Sqrt(d3), Math.Sqrt(1.0 - d3)));

   
}

Answer 1

我假设目的是使用一个简单的循环。 如果您使用的是 .net 的最新版本，则可以使用MinBy轻松完成此操作：

for(int i=0; i < 4; i++){
    var closest = locations.MinBy(l => GetDistance(l.Latitude, l.Longitude, searchLat, searchLong);
    Console.WriteLine(closest.Name);
    locations.Remove(closest);
}

更好的解决方案是计算到所有位置的所有距离并进行（部分）排序以获得 4 个最近的项目。 让您无需更改原始集合即可获得相同的结果。 但这似乎违背了任务的意图。