在列表中删除重复的对象（C＃） [英] Removing duplicate objects in a list (C#)

问题描述

所以我知道如何删除重复列表中时，它通过使用鲜明的（）从LINQ的涉及到字符串和INT等。但你如何删除基于对象的特定属性复制？

So I understand how to remove duplicates in a list when it comes to strings and int, etc by using Distinct() from Linq. But how do you remove duplicates based on a specific attribute of an object?

例如，我有一个 TimeMetric 类。这 TimeMetric 类有两个属性： MetricText 和 MetricTime 。我有 TimeMetrics 清单名为 MetricList 。我想删除任何重复 TimeMetric 用相同的 MetricText 属性。在 TimeMetric 值可以是相同的，但如果有 TimeMetric 有相同的 MetricText ，它必须不可复制的。

For example, I have a TimeMetric class. This TimeMetric class has two attributes: MetricText and MetricTime. I have a list of TimeMetrics called MetricList. I want to remove any duplicates TimeMetric with the same MetricText attribute. The TimeMetric value can be the same but if any TimeMetric has the same MetricText, it must be unduplicated.

推荐答案

您需要使用鲜明接受一个 的IEqualityComparer< TimeMetric> 实例作为第二个参数。这样定义一个比较器：

You need to use the second overload of Distinct that takes an IEqualityComparer<TimeMetric> instance as a second parameter. Define a comparer like this:

class MyComparer : IEqualityComparer<TimeMetric>
{
    public bool Equals(TimeMetric x, TimeMetric y)
    {
        return x.MetricText.Equals(y.MetricText);
    }

    public int GetHashCode(TimeMetric obj)
    {
        return obj.MetricText.GetHashCode();
    }
}

重要提示：的上面的代码不检查的情况下 MetricText 属性是空（和它听起来像它可能是，因为这是最有可能在字符串）。你应该做的，并返回 0 从的GetHashCode 如果 MetricText 为空。在另一方面，如果 MetricText 的类型是值类型，则不需要进行任何修改。

Important note: The above code does not check for the case where the MetricText property is null (and it sounds like it could be, since it's most probably a string). You should do that and return 0 from GetHashCode if MetricText is null. On the other hand, if the type of MetricText is a value type, you don't need to perform any modification.

和则：

var list = new List<TimeMetric> { ... };
var unique = list.Distinct(new MyComparer());

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