Question

猜猜我有两组

using System.Collections.Generic;

namespace ConsoleApplication
{
    internal class Student
    {
        public string Name;
        public string Surname;
        public int Mark;
    }

    internal class Program
    {
        private static void Main()
        {
            var twoGroups = new List<List<Student>>
            {
                new List<Student>
                {
                    new Student { Name = "Anna",  Surname = "Mors",  Mark = 4 }, 
                    new Student { Name = "Jimmy", Surname = "Lemon", Mark = 4 }
                },
                new List<Student>
                {
                    new Student { Name = "Anna",  Surname = "Mors",   Mark = 4 }, 
                    new Student { Name = "Tommy", Surname = "Wojski", Mark = 4 },
                    new Student { Name = "Jimmy", Surname = "Lemon",  Mark = 4 }
                }
            };
        }
    }
}

我如何通过linq从两个组（通过姓名或任何其他财产）获得独特的人？

显然有汤米，但我不知道如何用linq选择他（或选择一个独特的人名单。

UPD

另外，我可以选择只包含独特学生的小组。

using System.Collections.Generic;

namespace ConsoleApplication
{
    internal class GroupOfStudents
    {
        public string Code;
        public List<Student> Students;
    }

    internal class Student
    {
        public string Name;
        public string Surname;
        public int Mark;
    }

    internal class Program
    {
        private static void Main()
        {
            var twoGroups = new List<GroupOfStudents>
            {
                new GroupOfStudents
                {
                    Code = "A1",
                    Students = new List<Student>
                    {
                        new Student { Name = "Anna",  Surname = "Mors",  Mark = 4 }, 
                        new Student { Name = "Jimmy", Surname = "Lemon", Mark = 4 }
                    }
                },
                new GroupOfStudents()
                {
                    Code = "B2",
                    Students = new List<Student>
                    {
                        new Student { Name = "Anna",  Surname = "Mors",   Mark = 4 }, 
                        new Student { Name = "Tommy", Surname = "Wojski", Mark = 4 },
                        new Student { Name = "Jimmy", Surname = "Lemon",  Mark = 4 }
                    }
                }
            };
        }
    }
}

我想我需要选择学生并将他推到同名的新组，对吗？

Answer 1

将嵌套列表展开为一个SelectMany()
按唯一标准GroupBy()分组（我选择所有属性）
选择唯一记录Where()

代码：

List<Student> result = twoGroups.SelectMany(x => x)
                       .GroupBy(x => new { x.Name, x.Surname, x.Mark })
                       .Where(x => x.Count() == 1)
                       .Select(x => x.First())
                       .ToList();

Answer 2

您可以使用SelectMany，GroupBy和Count

IEnumerable<Student> uniqueStudents = twoGroups 
    .SelectMany(list => list)
    .GroupBy(student => student.Name)
    .Where(g => g.Count() == 1)
    .Select(g => g.First());

这仅选择在两个（或两个）列表中的一个中未多次包含的学生。

如果要按多个属性分组，请使用匿名类型

    .GroupBy(student => new { student.Name, student.Surname })

如果您想在同一个列表中允许重复，但不允许在多个列表中重复：

IEnumerable<Student> uniqueStudents = twoGroups 
    .SelectMany((list, index) => list.Select(student => new { student, index }))
    .GroupBy(x => x.student.Name)
    .Where(g =>
    {
        int index = g.First().index;
        return g.Skip(1).All(x => x.index == index);
    })
    .Select(g => g.First().student);

度Acc。您的修改

如果您要从同样出现在其他组中的列表中删除所有学生：

var studentNameLookup = twoGroups.SelectMany(g => g.Students).ToLookup(s => s.Name);
twoGroups.ForEach(g => g.Students.RemoveAll(s => studentNameLookup[s.Name].Count() > 1));

在组中查找唯一值

2 个答案: