Rx GroupBy：移除项目或更新exising项目不触发重组

Question

private static void TestGroupBy() 
     { 
      var rxList = new ReactiveList<int>(); 

      Observable.Merge(rxList.ItemsAdded, rxList.ItemChanged.Select(x => x.Sender)).GroupBy(i => i%3) 
       .Subscribe(group => 
       { 
        Console.WriteLine(string.Format("--> Group {0} is created", group.Key)); 
        int child = 0; 
        group.Subscribe(c => 
         { 
          Console.WriteLine(string.Format(" ------> Adding child {0} to Group {1} - ChildCnt: {2}", c, group.Key, ++child)); 
         }); 
       }); 

      Console.WriteLine("Add 1 to 10... "); 
      rxList.AddRange(new[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }); 

      Console.WriteLine("Change item 0 to 11, expect to be moved from group 0, to Group 2 "); 
      rxList[0] = 11; 

      Console.WriteLine("Remove item at 0, expect the item to be removed from the group ..."); 
      rxList.RemoveAt(0); 
     } 

我在这里有这段代码。如果项目被删除，或者项目被替换为新项目，我希望重新组合。我如何实现这一目标？

Answer 1

我不确定是否可以像使用groupBy一样执行项目移除。看看at this picture：看起来你想改变已经推送到“分组”流之一的元素。

在你的情况，我将简单地创建多个派生的集合（多达你有组），以不同的选择：

public void Test() 
{ 
    var source = new ReactiveList<int>(); 

    var derived1 = source.CreateDerivedCollection(x => x, filter: x => x%3 == 0); 
    var derived2 = source.CreateDerivedCollection(x => x, filter: x => x%3 == 1); 
    var derived3 = source.CreateDerivedCollection(x => x, filter: x => x%3 == 2); 
}