如何为C#字典中的多个键分配一个值？
c#
我想定义一个字母字典。在这本字典中，字符是键，每个字符都有一个值。我以最简单的方式编写了它，正如您所看到的，某些键具有相同的值。
var testDict =
new Dictionary <char, int>() {
{'A', 1}, {'E', 1}, {'I', 1},
{'O', 1}, {'U', 1}, {'L', 1},
{'N', 1}, {'R', 1}, {'S', 1},
{'T', 1},
{'D', 2}, {'G', 2},
{'B', 3}, {'C', 3}, {'M', 3}, {'P', 3},
{'F', 4}, {'H', 4}, {'V', 4}, {'W', 4}, {'Y', 4},
{'K', 5},
{'J', 8}, {'X', 8},
{'Q',10}, {'Z',10}};
我需要找到其中的字母并使用指定的值。我怎样才能以更简洁的方式编写它？
回答
甲字典<TKEY的，TValue>中是键和值的集合。在这个集合中，每个键都映射到一个值。它已经在 System.Collection.Generics 命名空间中实现。
另一方面，有一个名为Lookup<TKey, TElement>的集合，它表示键和值之间的一对多映射。即它将一个键映射到一个或多个值，并且它位于 System.Linq 命名空间中。
您可以转换任何在 System.Linq 命名空间中实现了IEnumerable接口和 ToLookup() 方法的集合，以构造Lookup<TKey, TElement>集合。
在有关 C# 语言的 Microsoft 教程中阅读有关查找集合和字典的更多信息。
在这个问题中，我们可以考虑一个包含两个字段的包，一个句子中的“字母表”字符及其“计数”。
class Package
{
public char Alphabet;
public int Counts;
}
然后构造Lookup数据结构：
public static void LookupExample()
{
// Create a dictionary of Packages to put into a Lookup data structure.
var testDict = new Dictionary <char, int>() {
new Package { Alphabet = 'A', Counts = 1},
new Package { Alphabet = 'B', Counts = 3},
new Package { Alphabet = 'C', Counts = 3},
new Package { Alphabet = 'D', Counts = 2},
new Package { Alphabet = 'E', Counts = 1},
new Package { Alphabet = 'F', Counts = 4},
new Package { Alphabet = 'G', Counts = 2},
new Package { Alphabet = 'H', Counts = 4},
new Package { Alphabet = 'I', Counts = 1},
new Package { Alphabet = 'J', Counts = 8},
new Package { Alphabet = 'K', Counts = 5},
new Package { Alphabet = 'L', Counts = 1},
new Package { Alphabet = 'M', Counts = 3},
new Package { Alphabet = 'N', Counts = 1},
new Package { Alphabet = 'O', Counts = 1},
new Package { Alphabet = 'P', Counts = 3},
new Package { Alphabet = 'Q', Counts = 10},
new Package { Alphabet = 'R', Counts = 1},
new Package { Alphabet = 'S', Counts = 1},
new Package { Alphabet = 'T', Counts = 1},
new Package { Alphabet = 'U', Counts = 1},
new Package { Alphabet = 'V', Counts = 4},
new Package { Alphabet = 'W', Counts = 4},
new Package { Alphabet = 'X', Counts = 8},
new Package { Alphabet = 'Y', Counts = 4},
new Package { Alphabet = 'Z', Counts = 10}};
// Create a Lookup to organize the packages. Use the Counts of each Alphabet as the key value.
// Select Alpahbet appended to each Counts in the Lookup.
Lookup<int, char> lookup = (Lookup<int, char>)testDict.ToLookup(p => p.Counts, p => p.Alphabet);
// Iterate through each IGrouping in the Lookup and output the contents.
foreach (IGrouping<int, char> packageGroup in lookup)
{
// Print the key value of the IGrouping.
Console.WriteLine(packageGroup.Key);
// Iterate through each value in the IGrouping and print its value.
foreach (char chr in packageGroup)
Console.WriteLine(" {0}", Convert.ToString(chr));
}
}
这有助于将“计数”视为新键并为其分配多个“字母”字符，这些字符的“计数”值具有相同的数量！