Linq-To-Objects分组依据

Question

我正在构建一个用于时间报告的软件

我有一台Dictionary<string, Dictionary<string, double>>。主字典中的关键字是用户名，它们的值是的字典。

我有一个函数GetDepartment(string UserName)，它返回一个包含用户部门的字符串。

我想要的是创建一个相同类型的新字典，它将部门作为主键，并且在子字典a中，其中小时是该部门的总和。

我一直在尝试用linq来做这件事，但没有成功。如果能得到一些帮助我会很高兴的！

编辑:这段代码做的正是我想要的。但是我想要在LINQ里

        Dictionary<string, Dictionary<string, double>> temphours = new Dictionary<string, Dictionary<string, double>>(); ;
        foreach (var user in hours)
        {
            string department = GetDepartment(user.Key);
            if (!temphours.ContainsKey(department))
            {
                temphours.Add(department, new Dictionary<string, double>());
            }
            foreach (var customerReport in user.Value)
            {
                if (!temphours[department].ContainsKey(customerReport.Key))
                {
                    temphours[department].Add(customerReport.Key, 0);
                }
                temphours[department][customerReport.Key] += customerReport.Value;
            }
        }

Answer 1

为什么你想用LINQ来做这个？我不认为它会更清晰，加上LINQ查询不太容易调试。

下面的表达式在LINQ to Entities中不起作用，因为您不能在LINQ to Entities中调用GetDepartment等C#函数。

Dictionary<string, Dictionary<string, double>> temphours 
    = (from user in hours
       group user by GetDepartment(user.Key) into department
       select new {
          Key = department.Key
          Value = (from userInDepartment in department
                   from report in userInDepartment.Value
                   group report by report.Key into g // To tired to think of a name =)
                   select new {
                       Key = g.Key
                       Value = g.Sum(reportInG => reportInG.Value)
                   }).ToDictonary(ud => ud.Key, ud=> ud.Value);
       }).ToDictonary(u => u.Key, u=> u.Value);

我不确定这是不是没有bug。至少它应该给你一个关于如何做到这一点的想法。

Answer 2

这是我对它的看法。

Dictionary<string, Dictionary<string, double>> temphours =
(
  from user in hours
  let department = GetDepartment(user.Key)
  from customerReport in user.Value
  group customerReport by department
)
.ToDictionary(
  g => g.Key,
  g => g.GroupBy(rep => rep.Key).ToDictionary
  (
    g2 => g2.Key,
    g2 => g2.Sum(rep => rep.Value)
  )
);

这是我力所能及的直通车。如果您想要更多的描述性，那么这可能为您提供了：

Dictionary<string, Dictionary<string, double>> temphours =
(
  from user in hours
  let department = GetDepartment(user.Key)
  from customerReport in user.Value
  group customerReport by department into reportGroup
  select new
  {
    Department = reportGroup.Key,
    Reports =
    (
       from report in reportGroup
       group report.Value by report.Key
    ).ToDictionary(g => g.Key, g => g.Sum())
  }
)
.ToDictionary{
  x => x.Department,
  x => x.Reports
);