c# - C# LINQ - 将嵌套字典转换为列表

Question

如何将嵌套字典展平为一些对象列表（SomeObject在以下示例中），这些对象应包含这些字典的键？

例如：让我们有一个以下类型的字典

var nestedDictionary = new Dictionary<int, Dictionary<int, string>>();

那么，让我们上这堂课

public class SomeObject
{
   public int var1;
   public int var2;
   public string someStringVar;
}

如何转换nestedDictionary为List<SomeObject>wherevar1是外部字典var2的键，是内部字典的键，是内部字典someStringVar的字符串值？

本质上，我如何转移这个：

nestedDict[0][0] = "foo";
nestedDict[0][1] = "bar";
nestedDict[0][2] = "foo1";
nestedDict[1][0] = "bar1";
nestedDict[1][1] = "foo2";
nestedDict[1][2] = "bar2";

对此（在伪 C# 中只是为了可视化它）

objList[0] = SomeObject { var1 = 0, var2 = 0, someStringVar = "foo" }
objList[1] = SomeObject { var1 = 0, var2 = 1, someStringVar = "bar" }
objList[2] = SomeObject { var1 = 0, var2 = 2, someStringVar = "foo1" }
objList[3] = SomeObject { var1 = 1, var2 = 0, someStringVar = "bar1" }
objList[4] = SomeObject { var1 = 1, var2 = 1, someStringVar = "foo2" }
objList[5] = SomeObject { var1 = 1, var2 = 2, someStringVar = "bar2" }

使用 LINQ？

Answer 1

您可以使用SelectMany()并编写如下内容：

var objList = nestedDictionary.SelectMany(
    pair => pair.Value.Select(
        innerPair => new SomeObject() {
            var1 = pair.Key,
            var2 = innerPair.Key,
            someStringVar = innerPair.Value
        })).ToList();

Answer 2

这应该有效：

var flattened =
from kvpOuter in nestedDictionary
from kvpInner in kvpOuter.Value
select new SomeObject()
{
    var1 = kvpOuter.Key,
    var2 = kvpInner.Key,
    someStringVar = kvpInner.Value
};
var list = flattened.ToList(); // if you need a list...

Answer 3

这会给你一个可枚举的IEnumerable<SomeObject>：

var results = from d in nestedDictionary
              from innerD in d.Value
              select new SomeObject { var1 = d.Key, var2 = innerD .Key, someStringVar = innerD .Value };

分别调用results.ToListorresults.ToArray来获取 aList<SomeObject>或SomeObject[]。

Answer 4

var xxx = nestedDictionary.SelectMany(
                    kvp =>
                    kvp.Value.Select(
                        xx => new SomeObject() {var1 = kvp.Key, var2 = xx.Key, someStringVar = xx.Value}));