C#-如何从集合视图中获取不同的项目 [英] C# - how to get distinct items from a Collection View

问题描述

CollectionView view = CollectionView)CollectionViewSource.GetDefaultView(MyData);
View.Filter = i => ((MyClass)i).MyProperty;

我有一个像上面一样的集合视图.问题是已经绑定到列表视图的MyData集合包含重复项.过滤后如何获得唯一的商品?

I have a collection view like in the above. The problem is that the collection MyData which has already been bound to a listview contains duplicate items. How do I get unique items as the result of my filtering?

推荐答案

此方法有效:

CollectionView view = (CollectionView)CollectionViewSource.GetDefaultView(c.Items);
view.Filter = i =>
{
    var index1 = c.MyData.FindIndex(delegate (MyClass s)
    {
        return Object.ReferenceEquals(s, i);
    });
    var index2 = c.MyData.FindLastIndex(delegate (MyClass s)
    {
        return ((MyClass)i).MyProperty == s.MyProperty as string; //value comparison
    });
    return index1 == index2;
};

index1 是对象在集合中的索引.您需要比较引用来获得.

index1 is the index of the object in the collection. You need to compare the references to get that.

index2 是 value 的最后一个索引.在那里，您需要比较 value .

index2 is the last index of the value. There you need to compare the value.

因此，您基本上可以比较当前 element 的 index 是否是它出现的最后一个索引.

So you basically compare if the index of the current element is the last one where it occurs.

注意:

这不适用于简单类型.我必须像这样初始化我的测试集合:

this does not work naturally with simple types. I had to initialize my test collection like this:

新列表< string>(){新字符串("I1" .ToCharArray())，新字符串("I1" .ToCharArray())，"I2"};

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