C＃清單 <Dictionary<string,string> &gt;-如何提取唯一的鍵/值對

Question

在C＃List>中，如何提取唯一的鍵/值對並將其存儲在List>中？

List<Dictionary<string,string>> md = new List<Dictionary<string,string>>();

輸入項

md [0]：

[0]:"A","Apple"
[1]:"B","Ball"

md [1]：

[0]:"A","Apple"
[1]:"B","Ball"

md [2]：

[0]: "C", "Cat"
[1]: "D", "Dog"

輸出量

md [0]：

[0]:"A","Apple"
[1]:"B","Ball"

md [1]：

[0]:"C" : "Cat"
[1]:"D" : "Dog"

需要提取唯一鍵/值對的代碼示例，而無需唯一鍵或唯一值。

（*注意：上面的[0]，[1]表示列表和字典中的索引，而不是鍵或值）

Answer 1

List<Dictionary<string,string>> md = new List<Dictionary<string,string>>();

var unique = new Dictionary<string, string>();

foreach (var m in md)
{
    foreach(var innerKey in m.Key)
    {
      if (!unique.ContainsKey(innerKey))
      {
        unique.Add(innerKey, m[innerKey]);
      }
    }
}

Answer 2

一種可能完全正確的解決方案是實現IEqualityComparer<Dictionary<string, string>> ：

public class DictionaryComparer : IEqualityComparer<Dictionary<string, string>>
{
    public int GetHashCode(Dictionary<string, string> d)
    {
        var hashCode = 17;
        foreach (var entry in d.OrderBy(kvp => kvp.Key))
        {
            hashCode = hashCode * 23 + entry.Key.GetHashCode();
            hashCode = hashCode * 23 + entry.Value.GetHashCode();
        }

        return hashCode;
    }

    public bool Equals(Dictionary<string, string> d1, Dictionary<string, string> d2)
    {
        string value2;
        return d1.Count == d2.Count && d1.All(kvp => d2.TryGetValue(kvp.Key, out value2) && kvp.Value == value2);
    }
}

然后獲取唯一字典列表：

var result = md.Distinct(new DictionaryComparer()).ToList();

Answer 3

您可以使用linq完成。

        List<Dictionary<string, string>> md = new List<Dictionary<string, string>>();
        md.Add(new Dictionary<string, string>() { { "A","Apple"}, { "B", "Ball" } });
        md.Add(new Dictionary<string, string>() { { "A","Apple"}, { "B", "Ball" } });
        md.Add(new Dictionary<string, string>() { { "C","Cat"}, { "D", "Dog" } });

        var filtered =
            md.GroupBy(x => string.Join("", x.Select(i => string.Format("{0}{1}", i.Key, i.Value)))).Select(x => x.First());

變量“已過濾”包含具有唯一集合的詞典列表。