c# - 在 C# 中使用 LINQ 比较字典

Question

我需要比较两个字典并用不匹配的项更新另一个字典

两个字典很像

Dictionary<String, List<String>> DICTONE = new Dictionary<string, List<String>>();
Dictionary<string, List<String>> DICTTWO = new Dictionary<string, List<String>>();

内容

DICTONE["KEY1"]="A"
                "B"
                "C"

DICTONE["KEY2"]="D"
                "E"
                "F"

DICTTWO["KEY1"]="A"
                "B"
                "Z"

DICTTWO["KEY3"]="W"
                "X"
                "Y"

第三个字典有一个类实例作为值

Dictionary<String, MyClass> DICTRESULT = new Dictionary<string, MyClass>();

类就像

class MyClass
{
    public List<string> Additional = null;
        public List<string> Missing = null; 

    public MyClass()
        {
            Additional = new List<string>();
            Missing = new List<string>();
        }
        public MyClass(List<string> p_Additional, List<string> p_Missing)
        {
            Additional = p_Additional;
            Missing = p_Missing;
        }
}

场景是

1. 如果一个项目在 DICTONE 中而不在 DICTTWO 中，则将该项目添加到 RESULTDICT 中的 MISSING 列表中
2. 如果一个项目在 DICTTWO 中而不在 DICTTONE 中，则将该项目添加到 RESULTDICT 中的附加列表

预期的答案是

DICTRESULT["KEY1"]=ADDITIONAL LIST ---> "Z"
                   MISSING LIST    ---> "C"

DICTRESULT["KEY2"]=ADDITIONAL LIST ---> ""
                   MISSING LIST    ---> "D"
                                        "E"
                                        "F"
DICTRESULT["KEY3"]=ADDITIONAL LIST ---> ""
                   MISSING LIST    ---> "W"
                                        "X"
                                        "Y"

有没有办法使用 LINQ 来做到这一点

Answer 1

好吧，这是一个尝试，假设 first 和 second 是有问题的字典。

var items = from key in first.Keys.Concat(second.Keys).Distinct()
            let firstList = first.GetValueOrDefault(key) ?? new List<string>()
            let secondList = second.GetValueOrDefault(key) ?? new List<string>()
            select new { Key = key,
                         Additional = secondList.Except(firstList),
                         Missing = firstList.Except(secondList) };
var result = items.ToDictionary(x => x.Key,
                                x => new MyClass(x.Additional, x.Missing));

请注意，这是完全未经测试的。我什至没有尝试编译它。它还需要一个额外的扩展方法:

public static TValue GetValueOrDefault<TKey, TValue>
    (this IDictionary<TKey, TValue> dictionary,
     TKey key)
{
    TValue value;
    dictionary.TryGetValue(key, out value)
    return value;
}