使用LINQ刪除字典中的重複和這些重複的計數

Question

我有一些代碼返回我的字典中的獨特元素，但我也想返回重複元素的計數。基本上將字典[key，uniqueelement]更改爲字典[uniqueelement，count]。這是我的代碼，只是返回獨特的元素。

var uniqueItems = deviceInstances.Children.GroupBy(pair => pair.Value.Information.UnderlyingDeviceType) 
        .Select(group => group.First()) 
        .ToDictionary(pair => pair.Key, pair => pair.Value.Information.UnderlyingDeviceType.ToString()); 

Answer 1

基於你已經在此基礎上演示

Dictionary<int, string> dictionary = new Dictionary<int, string>(); 
dictionary.Add(1, "Alpha"); 
dictionary.Add(2, "Bravo"); 
dictionary.Add(3, "Charlie"); 
dictionary.Add(4, "Alpha"); 
dictionary.Add(5, "Bravo"); 
dictionary.Add(6, "Alpha"); 

var uniqueItems = dictionary 
    .GroupBy(kvp => kvp.Value) 
    .Select(g => new { g.Key, Count = g.Count() }) 
    .ToDictionary(g => g.Key, g => g.Count); 

foreach (var kvp in uniqueItems) 
{ 
    Console.WriteLine("{0}\t{1}", kvp.Key, kvp.Value); 
} 

Answer 2

Dictionary<T, U> source = GetDictionary(); 

List<IGrouping<U, T> valueGroupList = source 
    .GroupBy(kvp => kvp.Value, kvp => kvp.Key) 
    .ToList(); 

Dictionary<T, U> withoutDupes = valueGroupList 
    .Where(g => !g.Skip(1).Any()) 
    .ToDictionary(g => g.First(), g.Key); 

Dictionary<U, int> dupesWithCount = valueGroupList 
    .Where(g => g.Skip(1).Any()) 
    .ToDictionary(g.Key, g.Count())