列表的交集

本文介绍了列表的交集的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

是否有更好，更优雅和简洁的方法来获取C#中两个列表的交集?

Is there a better, more elegant and concise, way to get the intersection of two lists in C#?

在C#中，一种计算日期列表交集的方法是:

In C# a method to calculate an intersection of list of dates is:

public List<DateTime> dates_common(Timeserie ts1, Timeserie ts2) { var dt1 = new HashSet<DateTime>(ts1.dates); var dt2 = new HashSet<DateTime>(ts2.dates); dt1.IntersectWith(dt2); var dt = new DateTime[dt1.Count]; dt1.CopyTo(dt); return new List<DateTime>(dt); }

在Ruby中，这样做是:

In Ruby one would do this as:

def dates_common(ts1, ts2) dt1 = ts1.dates.to_set dt2 = ts2.dates.to_set return dt1.intersection(dt2).to_a end

这种笨拙的根本原因是IEnumerable与具体容器和数组之间的不对称性.

The root cause of this clunkiness is the asymmetry between IEnumerable and concrete containers and arrays.

我一直惊讶于C#标准库的设计多么糟糕，因为这种问题一直在出现.

I am constantly amazed how badly designed C# standard libraries are as this kind of problems come up all the time.

有没有更好的方法，这意味着更优雅，更简洁的方法呢?

Is there a better, this means more elegant and concise, way to do this?

推荐答案

您可以使用 Enumerable.Intersect 和 Enumerable.ToList 扩展方法，如下所示，可以获得非常简洁明了的代码:

You can use the Enumerable.Intersect and Enumerable.ToList extension methods as follows to get very elegant and concise code:

public List<DateTime> dates_common(Timeserie ts1, Timeserie ts2) { return ts1.dates.Intersect(ts2.dates).ToList(); }