如何在 linq 中压平字典 <string,List<string>> 并将键保留在结果中

Question

你是如何在linq中实现以下功能的？我觉得应该有一个 Linq 替代品。

    var foods = new Dictionary<string, List<string>>();
    foods.Add("Cake", new List<string>() { "Sponge", "Gateux", "Tart" });
    foods.Add("Pie", new List<string>() { "Mud", "Apple" });
    foods.Add("Roll", new List<string>() { "Sausage" });

    var result = new List<Tuple<string, string>>();
    foreach (var food in foods)
    {
        foreach (var detail in food.Value)
        {
            result.Add(new Tuple<string, string>(food.Key, detail));
        }
    }

ie
cake <sponge, gateux>
pie <apple>

to

cake, sponge
cake, gateux
pie,  apple

谢谢

Answer 1

您可以使用SelectMany扩展方法：

var result= foods.SelectMany(f=>f.Value.Select(s=>new Tuple<string, string>(f.Key, s)))
                 .ToList();

Answer 2

 var result = (from food in foods 
               from detail in food.Value 
               select new Tuple<string, string>(food.Key, detail)).ToList();

Answer 3

Linq 是一个查询。这就是 'q' 所代表的意思。您正在将项目添加到字典中。试试这个

            Dictionary<string, List<string>> foods = new Dictionary<string, List<string>>()  { 
               {"cake",  new List<string>() {"Sponge", "Gateux", "Tart"}},
               {"Pie",  new List<string>() {"Mud", "Apple"}},
               {"Roll",  new List<string>() {"Sausage"}},
            };

如何在 linq 中压平字典 <string,List<string>> 并将键保留在结果中

How to flatten a dictionary<string,List<string>> in linq and keep the key in the results

c#

linq

dictionary

flatten