c# - 如何从嵌套字典中获取查找

Question

我有一个嵌套字典，我想从中派生一个查找。字典的示例数据如下：

var binary_transaction_model = new Dictionary<string, Dictionary<string, bool>>();
binary_transaction_model.Add("123", new Dictionary<string, bool>(){{"829L", false},{"830L", true}});
binary_transaction_model.Add("456", new Dictionary<string, bool>(){{"829L", true},{"830L", false}});
binary_transaction_model.Add("789", new Dictionary<string, bool>(){{"829L", true},{"830L", true}});

此 LINQ 语句正在工作：

var cols = from a in binary_transaction_model
    from b in a.Value
    where b.Value == true
    group a.Key by b.Key;

它给了我一个IEnumerable<IGrouping<String,String>>. 出于查找目的，我需要将此结果作为查找数据结构。我怎样才能做到这一点？签名应该是ToLookup()什么样子的？（编辑：我想要一个Lookup<String,String>。）

Answer 1

这应该有效：

var cols = (from a in binary_transaction_model
            from b in a.Value
            where b.Value == true
            select new { aKey = a.Key, bKey = b.Key })
            .ToLookup(x => x.bKey, x => x.aKey);