C# 如何按日期时间对字典进行分组并对int进行求和

我有以下代码：

    var tradeReqsBySegment = segGroups.Join(pPeriods, s => s.MarketSegmentId, p => p.EntityId, (s, p) => new
    {
        SegmentCode = s.SegmentCode, // string
        Time = p.StartLocal, // datetime
        TradeRequirement = p.Volume // double
    })
    .GroupBy(s => s.SegmentCode)
    .ToDictionary(g => g.Key, g => g.ToDictionary(i => i.Time, i=>i.TradeRequirement));

我希望将

g.ToDictionary（I=>I.Time，I=>I.TradeRequirement））

按时间分组，并将

TradeRequirement

相加或平均。我该如何处理这个问题

此外，是否可以按月对时间进行分组，如get：

Time - TradeReq
01/2013 - 500
02/2013 - 234
...

---

您可以使用匿名类型同时获取：

Sum

和

Average

：

var tradeReqsBySegment = segGroups.Join(pPeriods, s => s.MarketSegmentId, p => p.EntityId, (s, p) => new
{
    SegmentCode = s.SegmentCode, // string
    Time = p.StartLocal, // datetime
    TradeRequirement = p.Volume // double
})
.GroupBy(s => s.SegmentCode)
.ToDictionary(g => g.Key,
              g => g.GroupBy(gr => new DateTime(gr.Time.Year, gr.Time.Month, 1))
                    .ToDictionary(gr => gr.Key.ToString("MM/yyyy"),
                                  gr => new {
                                      Sum = gr.Sum(s => s.TradeRequirement),
                                      Avg = gr.Average(s => s.TradeRequirement)
                                  }));

---

请参阅按月份分组。确实非常有用。：）

var tradeReqsBySegment = segGroups.Join(pPeriods, s => s.MarketSegmentId, p => p.EntityId, (s, p) => new
{
    SegmentCode = s.SegmentCode, // string
    Time = p.StartLocal, // datetime
    TradeRequirement = p.Volume // double
})
.GroupBy(s => s.SegmentCode)
.ToDictionary(g => g.Key,
              g => g.GroupBy(gr => new DateTime(gr.Time.Year, gr.Time.Month, 1))
                    .ToDictionary(gr => gr.Key.ToString("MM/yyyy"),
                                  gr => new {
                                      Sum = gr.Sum(s => s.TradeRequirement),
                                      Avg = gr.Average(s => s.TradeRequirement)
                                  }));