将两个字典与LINQ结合在一起 [英] Combine two Dictionaries with LINQ

问题描述

我的问题已被标记为这个问题的可能重复：如何在c＃中添加2个字典内容而不循环

My question has been flagged as a possible duplicate of this question: How to add 2 Dictionary contents without looping in c#

我相信我的问题是不同的，因为我正在问如何组合两个字典以特定的方式：我想要Dictionary1中的所有项目以及Dictionary2中不存在的所有项目（即密钥不存在）。

I believe my question is different because I am asking how to combine two dictionaries in a particular way: I want all items from Dictionary1 plus all items from Dictionary2 that are not in (ie the key does not exist) in Dictionary1.

我有两个字典像这样：

var d1 = new Dictionary<string,object>();
var d2 = new Dictionary<string,object>();

d1["a"] = 1;
d1["b"] = 2;
d1["c"] = 3;

d2["a"] = 11;
d2["e"] = 12;
d2["c"] = 13;

我想将它们组合成一个新的字典（在技术上，它不一定是一个字典，它可能只是一个 KeyValuePairs 的序列），使得输出包含d1中的所有 KeyValuePairs ，只有来自 d2 的KeyValue对，其键不会出现在 d1 中。

I would like to combine them into a new Dictionary (technically, it does not have to be a dictionary, it could just be a sequence of KeyValuePairs) such that the output contains all of the KeyValuePairs from d1 and only the KeyValuePairs from d2 whose Key does not appear in d1.

概念：

var d3 = d1.Concat(d2.Except(d1))

但是，这是给我所有从d1和d2的元素。

But that is giving me all of the elements from d1 and d2.

似乎应该是很明显的，但是我一定是缺少一些东西。

Seems like it should be obvious, but I must be missing something.

推荐答案

使用 / code>默认情况下，它使用默认的相等性比较器，对于 KeyValuePair 类型比较键和值。您可以这样做：

When you use Except by default it uses the default equality comparer, which for the KeyValuePair type compares both the keys and the values. You could this approach instead:

var d3 = d1.Concat(d2.Where(kvp => !d1.ContainsKey(kvp.Key)));

这篇关于将两个字典与LINQ结合在一起的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！