c# - 如何在 linq 中展平字典 <string,List<string>> 并将键保留在结果中

Question

你如何在linq中实现以下功能？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();