c# - 使用 Linq 按列表中的多列分组并标记所有重复项

Question

我想使用 LinQ 查询列表并找到重复的人(定义了重复项具有相同的名字、姓氏和出生日期)并标记每个重复的人的StateOfData 属性包含字符串“duplicate”，每个人的 StateOfData 属性包含字符串“unique”。

public  Class Person 
{
public string PersonFirstName { get; set; }
public string PersonLastName { get; set; }
public datetime PersonDateOfBirth { get; set; }
public string StateOfData{ get; set }

public Person (string firstName, string lastName, dateTime dateOfBirth,string state)
{
    this.PersonFirstName  = firstName;
    this.PersonLastName = lastName;
    this.PersonDateOfBirth = dateOfBirth;
    this.StateOfData = state;
}


}


IList<Person> personsList  =  new List<Person>(); 
Person pers = new Person("Diane","Jones","1967-01-01","");
personsList.add(pers);
Person pers = new Person("Diane","Jones","1967-01-01","");
personsList.add(pers);
Person pers = new Person("John","Jones","1967-01-01","");
personsList.add(pers);

人员列表的结果应为:

“黛安”，“琼斯”，“1967-01-01”，“重复”
“黛安”，“琼斯”，“1967-01-01”，“重复”
“约翰”，“琼斯”，“1967-01-01”，“独一无二”

如有任何帮助，我们将不胜感激

Answer 1

var theLookup = personList
  .GroupBy(p => new {p.PersonFirstName, p.PersonLastName, p.PersonDateOfBirth})
  .ToLookup(g => g.Skip(1).Any() ? "duplicate" : "unique");

foreach(var lookupEntry in theLookup)
{
  string stateOfData = lookupEntry.Key;
  foreach(Person p in lookupEntry.SelectMany(g => g))
  {
    p.StateOfData = stateOfData;
  }
}