在C＃合并字典 [英] Merging dictionaries in C#

问题描述

什么是合并2个或更多的字典（词典＆LT ; T1，T2＆GT）的最佳方式在C＃中？
（3.0的功能，如LINQ的罚款）。

What's the best way to merge 2 or more dictionaries (Dictionary<T1,T2>) in C#? (3.0 features like LINQ are fine).

我的线沿线的思维方法签名

I'm thinking of a method signature along the lines of:

public static Dictionary<TKey,TValue>
                 Merge<TKey,TValue>(Dictionary<TKey,TValue>[] dictionaries);

或

public static Dictionary<TKey,TValue>
                 Merge<TKey,TValue>(IEnumerable<Dictionary<TKey,TValue>> dictionaries);

编辑：得到JaredPar和乔恩斯基特一个很酷的解决方案，但我在想东西处理重复键。在冲突的情况下，它并不重要价值，只要它的一贯被保存到字典。

Got a cool solution from JaredPar and Jon Skeet, but I was thinking of something that handles duplicate keys. In case of collision, it doesn't matter which value is saved to the dict as long as it's consistent.

推荐答案

这部分取决于你想，如果你遇到重复发生什么。例如，你可以这样做：

This partly depends on what you want to happen if you run into duplicates. For instance, you could do:

var result = dictionaries.SelectMany(dict => dict)
                         .ToDictionary(pair => pair.Key, pair => pair.Value);

如果您得到任何重复键，这将炸毁。

That will blow up if you get any duplicate keys.

编辑：如果您使用ToLookup，那么你会得到一个查找，可以有每个键多个值。您的可能的然后将其转换成一个字典：

If you use ToLookup then you'll get a lookup which can have multiple values per key. You could then convert that to a dictionary:

var result = dictionaries.SelectMany(dict => dict)
                         .ToLookup(pair => pair.Key, pair => pair.Value)
                         .ToDictionary(group => group.Key, group => group.First());

这是一个有点难看 - 和低效率的 - 但它是做在code而言最快捷的方式。 （我没有测试过，诚然。）

It's a bit ugly - and inefficient - but it's the quickest way to do it in terms of code. (I haven't tested it, admittedly.)

您可以编写自己的ToDictionary2扩展方法当然是（有​​一个更好的名字，但我没有时间现在想起来一） - 这是不是非常难做到，只是覆盖（或无视）重复键。最重要的一点（在我看来）使用的SelectMany，并意识到字典支持迭代对其键/值对。

You could write your own ToDictionary2 extension method of course (with a better name, but I don't have time to think of one now) - it's not terribly hard to do, just overwriting (or ignoring) duplicate keys. The important bit (to my mind) is using SelectMany, and realising that a dictionary supports iteration over its key/value pairs.

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