c# - 如何使用 LINQ C# 过滤列表

Question

我需要过滤 List<Students>进入StudentsWitHighestDebts .

标准是只有学生在ZachetDidNotPass有最大值和maximum-1总共List<Students>包含在结果中。

var StudentsWitHighestDebts = students
               .Where(s => s.ZachetDidNotPass.(some condition))
               .OrderBy(s => s.Name)
               .ToList();

例如，给定一个学生列表 ZachetDidNotPass值 0 1 2 5 6 7 .结果 StudentsWitHighestDebts应该只包含 7 and 6 的学生ZachetDidNotPass 中的值.

Answer 1

第一个选项:采取 2 个最高债务并通过 ZachetDidNotPass 过滤学生:

var highestDebts = students.Select(s => s.ZachetDidNotPass)
    .OrderByDescending(p => p).Take(2).ToArray();
var studentsWitHighestDebts = students
    .Where(s => highestDebts.Contains(s.ZachetDidNotPass))
    .OrderByDescending(s => s.ZachetDidNotPass).ToList();

第二个选项 - 按 ZachetDidNotPass 分组，按键降序对组进行排序，取前 2 个组并从组中选择学生

var studentsWitHighestDebts = students.GroupBy(s => s.ZachetDidNotPass)
    .OrderByDescending(g => g.Key).Take(2)
    .SelectMany(g => g).ToList();

第三个选项(带最高债务和highestDebt - 1的学生)

var highestDebt = students.Max(s => s.ZachetDidNotPass);

var studentsWitHighestDebts = students
    .Where(s => s.ZachetDidNotPass == highestDebt || s.ZachetDidNotPass == highestDebt - 1)
    .OrderByDescending(s => s.ZachetDidNotPass).ToList();