如何使用LINQ创建嵌套的分组字典? [英] How do I create a nested group-by dictionary using LINQ?

问题描述

如何使用LINQ为下表创建嵌套分组?我想按Code分组，然后按Mktcode分组.

How would I create a nested grouping for the table below, using LINQ? I want to group by Code, then by Mktcode.

Code Mktcode Id
==== ======= ====
1    10      0001 
2    20      0010 
1    10      0012 
1    20      0010 
1    20      0014 
2    20      0001
2    30      0002
1    30      0002
1    30      0005

最后我想要一本字典，就像

I'd like a dictionary, in the end, like

Dictionary<Code, List<Dictionary<Mktcode, List<Id>>>>

所以这本字典的值应该是

So the values of this dictionary would be

{1, ({10,(0001,0012)}, {20,(0010,0014)}, {30, (0002, 0005)})},
{2, ({20,(0001, 0010)}, {30, (0020)} )}

推荐答案

我会这样想:

• 您主要是按代码分组，因此请先这样做
• 对于每个组，您仍然可以获得结果列表-因此请在此处应用另一个分组.

类似的东西:

var groupedByCode = source.GroupBy(x => x.Code);

var groupedByCodeAndThenId = groupedByCode.Select(group =>
    new { Key=group.Key, NestedGroup = group.ToLookup
                                         (result => result.MktCode, result => result.Id));

var dictionary = groupedByCodeAndThenId.ToDictionary
    (result => result.Key, result => result.NestedGroup);

这将为您提供Dictionary<Code, Lookup<MktCode, Id>>-我认为这就是您想要的.不过，这是完全未经测试的.

That will give you a Dictionary<Code, Lookup<MktCode, Id>> - I think that's what you want. It's completely untested though.

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