c# – 使用LINQ按小时分组

我每隔15分钟就会在PowerStringHistorys和PowerCombinerHistorys表中记录数据.我是LINQ的新手,我正在试图弄清楚如何创建一个查询,按小时对我的数据进行分组,并且该小时平均当前.这是我到目前为止所拥有的

TimeZoneInfo easternZone = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
        DateTime UTC_StartingDate = TimeZoneInfo.ConvertTimetoUtc(StartingDate,easternZone);
        DateTime UTC_EndingDate = TimeZoneInfo.ConvertTimetoUtc(EndingDate,easternZone);

        var FirstQ = from p in db.PowerStringHistorys
                     join t in db.PowerStrings on p.string_id equals t.id
                     join u in db.PowerCombiners on t.combiner_id equals u.id
                     join s in db.PowerCombinerHistorys on p.recordTime equals s.recordTime
                     where p.recordTime >= UTC_StartingDate
                     where p.recordTime <= UTC_EndingDate
                     select new
                     {
                         Combiner = u.id,Current = p.current,RecordTime = p.recordTime,Voltage = s.voltage
                     };

现在我需要按组合器和小时进行分组,这样我就可以平均当前值,并为指定日期范围的每小时获得每个组合器的千瓦时.

我需要以某种方式在查询中应用这个简单的公式：
(平均瓦/小时)/ 1000 = Kwh

所以我将结束的是类似下面的内容.任何帮助将不胜感激.

Combiner 1     03/19/2012 1:0:0     1.85 Kwh
Combiner 1     03/19/2012 2:0:0     1.98 Kwh
Combiner 1     03/19/2012 3:0:0     2.05 Kwh
Combiner 1     03/19/2012 4:0:0     2.11 Kwh
Combiner 1     03/19/2012 5:0:0     2.01 Kwh
Combiner 1     03/19/2012 6:0:0     1.96 Kwh
Combiner 1     03/19/2012 7:0:0     1.85 Kwh
Combiner 2     03/19/2012 1:0:0     1.77 Kwh
Combiner 2     03/19/2012 2:0:0     1.96 Kwh
Combiner 2     03/19/2012 3:0:0     2.03 Kwh
Combiner 2     03/19/2012 4:0:0     2.11 Kwh
Combiner 2     03/19/2012 5:0:0     2.02 Kwh
Combiner 2     03/19/2012 6:0:0     1.98 Kwh
Combiner 2     03/19/2012 7:0:0     1.83 Kwh
Combiner 3     03/19/2012 1:0:0     1.77 Kwh
Combiner 3     03/19/2012 2:0:0     1.96 Kwh
Combiner 3     03/19/2012 3:0:0     2.03 Kwh
Combiner 3     03/19/2012 4:0:0     2.11 Kwh
Combiner 3     03/19/2012 5:0:0     2.02 Kwh
Combiner 3     03/19/2012 6:0:0     1.98 Kwh
Combiner 3     03/19/2012 7:0:0     1.83 Kwh

编辑

以上是我原来的问题.在处理了我收到的两条建议后,我最终得到了下面显示的代码.现在我只是将日期和总Kwhs返回到视图中.我计划将stringGroupedKwhlist列表抛出到HighChart中,以便用户查看并将firstQ查询结果抛出到Telerik网格中,以便用户对其进行过滤/排序/分组,以便他们可以处理详细信息.虽然代码确实有效并产生我期望的结果,但我不确定它是否有效.由于我必须循环使用foreach,我猜测一旦获得大量数据,它可能会变慢.有没有更有效的方法来处理这个？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using AESSmart.Models;

namespace AESSmart.Controllers
{
    public class StringKwh
    {
        public int CombinerID;
        public int StringID;
        public DateTime Interval;
        public Double KWH;

        public StringKwh(int combiner,int stringid,DateTime interval,double kwh)
        {
            CombinerID = combiner;
            StringID = stringid;
            Interval = interval;
            KWH = kwh;
        }
    }

    public class HomeController : Controller
    {
        private readonly AESSmartentities db = new AESSmartentities();

        public ActionResult Index()
        {
            //REPRESENTS DATE RANGE FOR A FULL DAY
            DateTime startingDate = new DateTime(DateTime.Now.Year,DateTime.Now.Month,DateTime.Now.Day,1);
            DateTime endingDate = new DateTime(DateTime.Now.Year,23,59,59);

            TimeZoneInfo easternZone = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
            DateTime utcStartingDate = TimeZoneInfo.ConvertTimetoUtc(startingDate,easternZone);
            DateTime utcEndingDate = TimeZoneInfo.ConvertTimetoUtc(endingDate,easternZone);

            var firstQ = from p in db.PowerStringHistorys 
                         from s in db.PowerCombinerHistorys
                         join t in db.PowerStrings on p.string_id equals t.id
                         join u in db.PowerCombiners on t.combiner_id equals u.id
                         where p.recordTime == s.recordTime
                         where p.recordTime >= utcStartingDate
                         where p.recordTime <= utcEndingDate
                         select new
                         {
                             Combiner = u.id,StringId = p.string_id,Voltage = s.voltage
                         };

            var groups = firstQ.ToList().GroupBy(q => new 
                                                { 
                                                    q.Combiner,q.StringId,Date = q.RecordTime.Date,Hour = q.RecordTime.Hour 
                                                });

            List<StringKwh> stringGroupedKwhlist = new List<StringKwh>();

            foreach (var group in groups)
            {
                stringGroupedKwhlist.Add(new StringKwh(
                                         group.Key.Combiner,group.Key.StringId,new DateTime(group.Key.Date.Year,group.Key.Date.Month,group.Key.Date.Day,group.Key.Hour,0),group.Average(g => g.Voltage * g.Current) / 1000d
                                         ));
            }

            var groupCombiner = stringGroupedKwhlist.GroupBy(q => new { q.CombinerID });
            double myTotalKwh = 0;

            foreach (var combinerGroup in groupCombiner)
            {
                myTotalKwh = Math.Round(combinerGroup.Sum(g => g.KWH),3);
            }

            ViewBag.LifeTimeGeneration = myTotalKwh;
            ViewBag.myUTCStartDate = utcStartingDate;
            ViewBag.myUTCEndDate = utcEndingDate;

            return View();
        }

        public ActionResult About()
        {
            return View();
        }
    }
}

// Group by combiner ID,date,and hour
var groups = FirstQ.ToList()
    .GroupBy(q => new 
        { q.Combiner,Hour = q.RecordTime.Hour });

foreach (var group in groups)
{
    var combinerId = group.Key.Combiner;
    var interval = new DateTime(group.Key.Date.Year,0);

    // power = voltage * current
    var kwh = group.Average(g => g.Voltage * g.Current) / 1000d;
}