Question

我有N个＆＃34;人物＆＃34;的清单。人们有2个属性：Id和Name。我想找到所有N个列表中包含的人员。我只想匹配Id。

以下是我的出发点：

List<People> result = new List<People>();

//I think I only need to find items in the first list that are in the others
foreach (People person in peoplesList.First()) {

    //then this is the start of iterating through the other full lists
    foreach (List<People> list in peoplesList.Skip(1)) {

        //Do I even need this?

    }
}

我被困在试图将头围绕中间部分。我只想要peoplesList.Skip(1)中每个列表中的内容。

Answer 1

数学上讲;您正在寻找所有列表之间的集合交集。幸运的是，LINQ有一个Instersect方法，所以你可以迭代地交叉你的集合。

List<List<People>> lists; //Initialize with your data
IEnumerable<People> commonPeople = lists.First();
foreach (List<People> list in lists.Skip(1))
{
   commonPeople = commonPeople.Intersect(list);
}
//commonPeople is now an IEnumerable containing the intersection of all lists

要使“ID”选择器正常工作，您需要为IEqualityComparer实施People

IEqualityComparer<People> comparer = new PeopleComparer();
...
commonPeople = commonPeople.Intersect(list, comparer);

IEqualityComparer的实际实施因为非常简单而遗漏了。

在N列表中查找公共对象

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