使用LINQ比较两个数组 [英] Compare two arrays using LINQ

问题描述

例如，我有两个数组:

string[] arrayOne = {"One", "Two", "Three", "Three", "Three"};
string[] arrayTwo = {"One", "Two", "Three"};

var result = arrayOne.Except(arrayTwo);

foreach (string s in result) Console.WriteLine(s);

我想要 arrayOne 中的项目，这些项目不在 arrayTwo 中.所以这里我需要的结果是: 三三 但由于将三"视为通用而不检查其他两个项目(三"，三")，因此我没有任何结果.

I want Items from arrayOne which are not there in arrayTwo. So here I need result as: Three Three but I am getting no results as its treating "Three" as common and not checking the other two items("Three", "Three").

我不想最终写出一个巨大的方法来解决这个问题.在SO上尝试了其他几个答案，但没有按预期工作:(.

I dont want to end up writing a huge method to solve this. Tried couple other answer on SO but didnt worked as expected :(.

谢谢！

推荐答案

构建第二个HashSet，如果无法从HashSet中删除该项目，则过滤第一个仅允许的项目.

Build a HashSet of the second, and then filter the first only allowing items if you can't remove the item from the HashSet.

var hs = new HashSet<string>(arrayTwo);
var filtered = arrayOne.Where(item => !hs.Remove(item)).ToArray();

考虑到注释中的额外要求，在这里很好地使用了 ILookup .

Taking account of your extra requirements in the comments, some nifty use of ILookup works nicely here.

var lookup1 = arrayOne.ToLookup(item => item);
var lookup2 = arrayTwo.ToLookup(item => item);
var output = lookup1.SelectMany(i => i.Take(i.Count() - lookup2[i.Key].Count())).ToArray();

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