C# 在C语言中,从这个集合中过滤出来的最佳方法是什么?
我有一个房间对象列表,每个房间对象都有一个建筑属性C# 在C语言中,从这个集合中过滤出来的最佳方法是什么?,c#,collections,C#,Collections,我有一个房间对象列表,每个房间对象都有一个建筑属性 public class Room { public string BuildingName; public string Name } 我现在想过滤我的收藏,我只从每栋楼拿走一个房间,我不在乎哪一个 比如说 var room = new Room(){BuildingName ="Building 1", Name = "Room 1"}; var room2 = new Room(){BuildingNam
public class Room
{
public string BuildingName;
public string Name
}
我现在想过滤我的收藏,我只从每栋楼拿走一个房间,我不在乎哪一个
比如说
var room = new Room(){BuildingName ="Building 1", Name = "Room 1"};
var room2 = new Room(){BuildingName ="Building 1", Name = "Room 2"};
var room3 = new Room(){BuildingName ="Building 2", Name = "Room 3"};
var room4 = new Room(){BuildingName ="Building 2", Name = "Room 4"};
var room5 = new Room(){BuildingName ="Building 2", Name = "Room 5"};
var ListofRooms = new List<Room> {room, room2, room3, room4, room5};
在本例中,我希望通过一个函数运行此列表,该函数将返回一个包含两个项目的数组,每个建筑一个项目
var result = ListofRooms.GroupBy(room => room.BuildingName)
.Select(buildingGroup => buildingGroup.First())
.ToList();
这样做的目的是为包含建筑中房间的每个建筑创建一个bucket,然后从每个bucket中选择一个房间,最后将所选房间具体化为一个集合
一些切点:
标准C命名约定规定,局部变量应在camelCase listOfRooms中命名,而不是在PasCalcalCaseListofRooms中命名。
如果愿意,可以在对象初始值设定项中消除无参数构造函数的偏执,如下所示:new Room{BuildingName=Building 1,Name=Room 1}
如果您不想为此使用LINQ,我会:
var seenBuildingNames = new HashSet<string>();
var result = new List<Room>();
foreach(var room in ListofRooms)
{
if(seenBuildingNames.Add(room.BuildingName))
{
// First time we are encountering this building; add room to result.
result.Add(room);
}
}
您可以使用这种方法:
var result = ListofRooms.Distinct(new BuildingEqualityComparer());
类BuildingEqualityComparer如下所示:
public class BuildingEqualityComparer : IEqualityComparer<Room>
{
public bool Equals(Room x, Room y)
{
return x.BuildingName.Equals(y.BuildingName);
}
public int GetHashCode(Room obj)
{
return obj.BuildingName.GetHashCode();
}
}
这种方法实际上很少使用,因为您需要实现IEqualityComparer,这是一种PITA,但它只是实现您所需的另一种方法,所以如果您喜欢它或觉得它更简单,请使用它