LINQ将字典转换为查找 [英] LINQ Convert Dictionary to Lookup

问题描述

我有一个类型为的变量字典< MyType，List< MyOtherType>>

我想将其转换为 Lookup< MyType，MyOtehrType> 。

我想先使用Lambda函数，平铺字典，然后将其转换为Lookup ToLookup（）。我被困在字典里。我想到使用SelectMany，但不能让它工作。任何人都有一个想法如何做？

I wanted to use Lambda functions to first, flatten the dictionary and then convert this to Lookup using the ToLookup(). I got stuck with the dictionary. I thought about using SelectMany but can't get it working. Anyone has got an idea how to do it?

推荐答案

如何：

var lookup = dictionary.SelectMany(pair => pair.Value,
                                   (pair, Value) => new { pair.Key, Value })
                       .ToLookup(pair => pair.Key, pair => pair.Value);

当字典已经具有所有信息分组时，确实感觉到有点浪费适当地，但我看不到一个简单的方法。当然，您可以使用字典周围的包装来实现 ILookup< TKey，TValue>

It does feel like a little bit of a waste doing this when the dictionary already has all the information grouped appropriately, but I can't see a simple way round that. Of course you could implement ILookup<TKey, TValue> yourself with a wrapper around the dictionary...

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