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Linq到对象分组依据

group-by linq c#

Oskar Kjellin · 技术社区 · 15 年前

我在建一个报时软件

我有一个 Dictionary<string, Dictionary<string, double>> . 主字典中的键是用户名,其值是的字典。

我有一个函数GetDepartment(stringusername),它返回一个带有用户部门的字符串。

我想要的是装箱一本新字典,类型相同,以部门为主键,在子字典a中,小时数是该部门的总小时数。

我一直在尝试用linq做这个,但是没有成功。很高兴能在这里得到帮助!

编辑:这个代码正是我想要的。但我想把它放在林肯

        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;
            }
        }

2 回复 | 直到 15 年前

Jens 15 年前

下面的表达式在LINQ to Entities中不起作用,因为您不能在那里调用诸如GetDepartment之类的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);

我不确定这是没有错误的。至少它应该给你一个如何做到这一点的想法。

Amy B 15 年前

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)
  )
);

那是我能做的最直接的事了。如果你想要更多的描述,那么这可能对你有用:

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
);

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