如何将泛型列表作为值添加到字典中<；字符串，列表<；餐厅>>；在c#.net中

本文关键字：lt gt 列表 net 字符串 餐厅 字典 泛型 添加 | 更新日期: 2023-09-27 18:01:15

public static void InitialiseRestaurantList(Dictionary<string, List<Restaurant>> allRestaurants)
        {
            var restaurants = new List<Restaurant>();
            using (var sr = new StreamReader(@".'Restaurants.csv"))
            {
                while (sr.Peek() != -1)
                {
                    var line = sr.ReadLine();
                    var fields = line.Split(',');
                    var obj = new Restaurant(fields[0], fields[1], fields[2], fields[3], fields[4]);
                    restaurants.Add(obj);
                }               
                sr.Close();
            }
            List<Restaurant> PuneList = new List<Restaurant>();
            foreach (Restaurant r in restaurants)
            {
                if (r.City.CompareTo("Pune")==0)
                {
                    PuneList.Add(r);
                }
            }
            Dictionary<string, List<Restaurant>> newDict = new Dictionary<string, List<Restaurant>();
            **// How to add the PuneList as a value to this newDict...?**     
      }

Restaurant.csv包含以下数据：

1,Mc Donald's,Pune,Kothrud,Near Karve Statue-29 
2,Dominoes,Pune,Baner,Sappehire Chamber Pune-45 
3,Faaso's,Pune,Kothrud,Karishma Society Karve Road Pune-29 
4,Pizza Hut,Nagpur,Dharampeth,Laxmibhawan Square Nagpur-10 
5,KFC,Nagpur,Ram Nagar,Near Nagpur University Nagpur-10 
6,MainLand China,Nagpur,Azim Nagar,Near Guru Nanak College of Pharmacy Nagpur-10 
7,Barbeque Nation,Goa,Margao,Near Majorda Beach Goa-01 
8,Sigree,Goa,Mapusa,Near Vagator Beach Goa-07 
9,Marakesh,Hyderabad,CBI Colony,Jubilee Hills Hyderabad-33 
10,Yana's,Hyderabad,Secundarabad,Near Mallanna Temple Hyderabad-03

我已经将csv文件中的值放入一个通用的餐厅列表类型中，其中有5个字段放入一个列表中，现在我想将列表中的一个城市作为关键字，将列表的其余字段作为值，并将其作为参数传递给Dictionary。有人能帮我这样做吗？我可以按地区城市列出单独的餐厅名单。如何将泛型列表作为值传递给字典。

如何将泛型列表作为值添加到字典中<；字符串，列表<；餐厅>>；在c#.net中

当您声明字典时，可以使用初始值设定项语法将项添加到字典中：

var newDict = new Dictionary<string, List<Restaurant>() {{"Pune", PuneList }};

然而，我相信最后10行左右的代码可以通过一些LINQ:来简化

var newDict = restaurants.Where(r => r.City.CompareTo("Pune") == 0)
                         .GroupBy(r => r.City)
                         .ToDictionary(r => r.Key, r => r.ToList());

编辑

一旦你将所有餐厅加载到列表中，你就可以将它们投影到一个由城市名称键入的Dictionary中，然后你可以使用字典根据关键字(城市(进行搜索并迭代餐厅(我简化了你的Restaurant(：

 var restaurants = new List<Restaurant>
    {
       new Restaurant("Pune", "Mc Donald's", "Pune Address #1"),
       new Restaurant("Pune", "Dominoes", "Pune Address #2"),
       new Restaurant("Nagpur", "Pizza Hut", "Nagpur Address #1")
    };
 var newDict = restaurants.GroupBy(r => r.City)
                          .ToDictionary(r => r.Key, r => r.ToList());
 foreach (var restaurant in newDict["Pune"])
 {
    Debug.WriteLine("City {0}, Address {1}, Brand {2}", restaurant.City, 
                    restaurant.Address, restaurant.Brand);
 }

输出：

City Pune, Address Pune Address #1, Brand Mc Donald's
City Pune, Address Pune Address #2, Brand Dominoes

只需使用"add"将其添加到字典中。

newDict.Add("Pune", PuneList);

然后您可以通过以下方式访问：

var puneList = newDict["Pune"];

如果你想检查字典是否包含密钥用法：

bool hasPune = newDict.ContainsKey("Pune");

点击此处阅读有关通用词典的更多信息。

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