Dictionary<List<string>, string> myDictionary = new Dictionary<List<string>, string>
{
{ new List<string> { "blackberries", "orange", "watermelon", "apple" }, "fruits" },
{ new List<string> { "spinach", "kale", "celery", "tomato", "red onion" }, "veggies" },
{ new List<string> { "almonds", "walnuts", "fish oil", "nut butter" }, "fats" },
{ new List<string> { "oatmeal", "brown rice", "beans", "lentils" }, "carbs" },
{ new List<string> { "beef", "chicken", "eggs", "salmon", "mackerel" }, "proteins" },
};
用例是打入字符串并查看其存在于哪个键中并吐出正确的值。例如:
var temp = myDictionary[new List<string> { "beans" }];
温度返回碳水化合物。
尽管当前的结构方式如此,但它不能工作,因为{beans}不存在,key
是key
的一部分。
哪种类型最适合此类数据使用?
答案 0 :(得分:2)
“ beans”应为键,“ carb”为值。密钥应该是简单类型,其值可能很复杂。在您的情况下都不应该。只需使用字典,其中食物是关键,食物的类型就是价值。您不必在键内搜索即可找到与之关联的值。在您的示例中,您必须遍历所有键,然后搜索匹配的键,然后获取值。这破坏了拥有钥匙的目的。
翻转它,以便食物类型成为找到食物清单的关键,然后构建一个Dictionary,您可以在其中基于食物查找食物类型。
是的,LINQ可以完成各种奇妙的事情,但是除非您正确地构造事物,否则到达那里将会很慢。这是您在任一方向上查找所需内容的最快方法。
var myDictionary = new Dictionary<string, List<string>>
{
{ "fruits", new List<string> { "raspberries", "blackberries", "blueberries", "orange", "watermelon", "apple", "strawberries" } },
{ "veggies", new List<string> { "spinach", "kale", "carrots", "celery", "tomato", "red onion" } },
{ "fats", new List<string> { "almonds", "walnuts", "fish oil", "nut butter" } },
{ "carbs",new List<string> { "oatmeal", "brown rice", "beans", "lentils" } },
{ "proteins", new List<string> { "beef", "chicken", "eggs", "salmon", "mackerel" } },
};
var myFoodIndex = new Dictionary<string, string>();
foreach(var key in myDictionary.Keys)
{
foreach (var foodType in myDictionary[key])
myFoodIndex.Add(foodType, key);
}
Console.WriteLine(myFoodIndex.ContainsKey("beans") ? myFoodIndex["beans"] : "Not Found");
Console.ReadKey();
我应该补充一点,如果要订购列表,请使用SortedDictionary或SortedList。详细了解here各自的优点和缺点。
答案 1 :(得分:0)
var myItems = new Tuple<List<string>, string>[]
{
new Tuple<List<string>, string>(new List<string> { "raspberries", "blackberries", "blueberries", "orange", "watermelon", "apple", "strawberries" }, "fruits" ),
new Tuple<List<string>, string>(new List<string> { "spinach", "kale", "carrots", "celery", "tomato", "red onion" }, "veggies" ),
new Tuple<List<string>, string>(new List<string> { "almonds", "walnuts", "fish oil", "nut butter" }, "fats" ),
new Tuple<List<string>, string>(new List<string> { "oatmeal", "brown rice", "beans", "lentils" }, "carbs" ),
new Tuple<List<string>, string>(new List<string> { "beef", "chicken", "eggs", "salmon", "mackerel" }, "proteins" ),
};
var myDictionary = myItems.SelectMany(t => t.Item1.Select(item => new {item, type = t.Item2}))
.ToDictionary(a => a.item, a => a.type);
Console.WriteLine(myDictionary["spinach"]);
答案 2 :(得分:0)
由于Dictionary<TKey, TValue>
实现了IEnumerable<KeyValuePair<TKey, TValue>>
,因此您可以使用LINQ对数据进行操作。
在这种情况下,您的键是List<string>
,而List.Contains
将使您检查列表中是否有字符串。找到匹配的条目后,您只需抓住该对中的Value
个成员。由于KeyValuePair<>
是一种值类型,因此您不必担心FirstOrDefault
的空返回值,因此我们可以使用它:
var value = myDictionary.FirstOrDefault(kv => kv.Key.Contains("beans")).Value;
如果未找到要搜索的字符串(在这种情况下为“ beans”),则输出将为空。
关于数据结构...
Dictionary<List<string>, string>
是一个奇怪的选择。除了开销之外,您几乎从对象中什么也得不到。您不能使用Dictionary<>
方法来获取数据,您的“键”不易搜索,等等。
对于带有少量装饰的普通存储以便于阅读,您可以像这样使用新的ValueTuple<>
类的数组:
(string Category, string[] Items)[] foods = new[] {
("fruits", new[] { "raspberries", "blackberries", "blueberries", "orange", "watermelon", "apple", "strawberries" }),
( "veggies", new[] { "spinach", "kale", "carrots", "celery", "tomato", "red onion" }),
( "fats", new[] { "almonds", "walnuts", "fish oil", "nut butter" }),
( "carbs", new[] { "oatmeal", "brown rice", "beans", "lentils" }),
( "proteins", new[] { "beef", "chicken", "eggs", "salmon", "mackerel" }),
};
这是一个包含一些编译时内容的数组,以使其更易于访问。查找基本上是相同的:
var value = foods.FirstOrDefault(_ => _.Items.Contains("beans")).Category;
许多方法中的只有一种。如果没有有关实际用例的更多信息,您将有太多的选择。