Linq Groupby 分类，但我如何操作集合中的值答案

【问题标题】：Linq Groupby categorizes but how do I manipulate the values in the collectionLinq Groupby 分类，但我如何操作集合中的值
【发布时间】：2013-07-03 15:09:54
【问题描述】：

我有一个可观察的 Auctions 集合，它的 Auction 类型看起来像

public class Auction
{
     public int GroupId {get; set;}
     public DateTime Date {get; set;}
     public string Hour {get; set;}
     public decimal Offer {get; set;}
     public decimal Bid {get; set;}
     public decimal OfferPrice {get; set;}
     public decimal BidPrice {get; set;}
}

该集合包含以下数据，

Group Id    Date    Hour    Offer   Bid Offer Price Bid Price
1   27/06/2013  00:00   5.556   86.3    250 0
1   27/06/2013  00:15   0   0   250 0
1   27/06/2013  00:30   0   0   250 0
1   27/06/2013  00:45   0   0   250 0
1   27/06/2013  01:00   0   0   250 0
1   27/06/2013  01:15   5.556   86.3    250 0
2   27/06/2013  01:30   8.68    19.9    100 20
2   27/06/2013  01:45   0   0   100 20
2   27/06/2013  02:00   8.68    19.9    100 20
2   27/06/2013  02:15   0   0   100 20
2   27/06/2013  02:30   8.68    19.9    100 20
2   27/06/2013  02:45   0   0   100 20
2   27/06/2013  03:00   8.68    19.9    100 20
3   27/06/2013  03:15   87.14   87.1    150 0
3   27/06/2013  03:30   0   0   150 0
3   27/06/2013  03:45   0   0   150 0
3   27/06/2013  04:00   0   0   150 0
3   27/06/2013  04:15   0   0   150 0
3   27/06/2013  04:30   0   0   150 0
3   27/06/2013  04:45   0   0   150 0
3   27/06/2013  05:00   0   0   150 0

现在我要做的是，

按 GroupId 分组集合，所以我得到 3 个块，其中一个 GroupId = 1、GroupId =2 和 GroupId = 3。
然后我需要将不在第 1 组中的所有内容设置为零并将其添加到第 1 组。

例子，

绿色组 1 中的所有内容都按原样复制，然后将组 1 附加其余数据但设置为零。
第 2 组和第 3 组也是如此。

通过 Linq 执行此操作的最佳方法是什么？

需要添加结果的集合是BOD类型，它包含

Public class BOD
{
    public DateTime Date {get; set;}
    public string Time {get; set;}
    public decimal Volume {get; set;}
    public decimal Price {get; set;}
}

【问题讨论】：

我们应该从哪里获得 BOD 对象的数量和价格？应该是报价还是投标？还是一个 Auction 对象应该变成两个 BOD 对象？
您好，所以 BOD 对象应该为每个组创建一个报价和一个投标。所以在上面的例子中，BOD 中有 6 个项目，第 1 组报价，投标，然后第 2 组报价，投标，然后第 3 组报价，投标。

标签： c# .net linq

【解决方案1】：

您可以将拍卖列表加入到唯一的 GroupId 列表中：

var q = (from a in Auctions
         from g in (Auctions.Select(aa=>aa.GroupId).Distinct())
         orderby g, a.Date, a.Hour
         select new Auction
             {
                  GroupId = g,
                  Date = a.Date,
                  Hour = a.Hour,
                  Offer      = a.GroupId == g ? a.Offer : 0,
                  Bid        = a.GroupId == g ? a.Bid : 0,
                  OfferPrice = a.GroupId == g ? a.OfferPrice : 0,
                  BidPrice   = a.GroupId == g ? a.BidPrice : 0
              }

【讨论】：

【解决方案2】：

你可以试试这样的：

var list = new List<YourType>(); // Your data source
var groupedList = list.GroupBy(listEntry => listEntry.GroupId);

foreach(var groupList in groupedList)
{
   var unionList = groupList.ToList()
       .Union(list.Where(listEntry => listEntry.GroupId != groupList.Key)
       .Select(listEntry => new YourType { GroupId = groupList.Key, a = 0, b = 0, c = listEntry.c }))
}

【讨论】：

需要将结果添加到BOD类型的集合中，该集合的类型与应用groupBy的集合不同。在这种情况下，联合将不起作用
好主意，在之前添加另一个选择就可以了。干杯伙伴。

【解决方案3】：

这样的事情应该可以工作：

var group1 =
            (from a in auctions where a.GroupId == 1 select a).Union(
                from a in auctions
                where a.GroupId != 1
                select new Auction { GroupId = 1, Date = a.Date, Hour = a.Hour });

除非您专门复制它们，否则新的拍卖将包含零。您希望摆脱硬编码的 id，但这并不难解决。

【讨论】：

需要将结果添加到BOD类型的集合中，该集合的类型与应用groupBy的集合不同。在这种情况下，联合将不起作用

【解决方案4】：

我不确定我是否正确地添加了来自其他组的项目，但请查看以下查询：

var auctions = new List<Auction>
{
    new Auction {GroupId = 1, Date = DateTime.Parse("27/06/2013"), Hour = "00:00", Offer = 5.556m, Bid = 86.3m, OfferPrice = 250m, BidPrice = 0m},
    new Auction {GroupId = 1, Date = DateTime.Parse("27/06/2013"), Hour = "00:15", Offer = 0m, Bid = 0m, OfferPrice = 250m, BidPrice = 0m},
    new Auction {GroupId = 1, Date = DateTime.Parse("27/06/2013"), Hour = "00:30", Offer = 0m, Bid = 0m, OfferPrice = 250m, BidPrice = 0m},
    new Auction {GroupId = 1, Date = DateTime.Parse("27/06/2013"), Hour = "00:45", Offer = 0m, Bid = 0m, OfferPrice = 250m, BidPrice = 0m},
    new Auction {GroupId = 1, Date = DateTime.Parse("27/06/2013"), Hour = "01:00", Offer = 0m, Bid = 0m, OfferPrice = 250m, BidPrice = 0m},
    new Auction {GroupId = 1, Date = DateTime.Parse("27/06/2013"), Hour = "01:15", Offer = 5.556m, Bid = 86.3m, OfferPrice = 250m, BidPrice = 0m},
    new Auction {GroupId = 2, Date = DateTime.Parse("27/06/2013"), Hour = "01:30", Offer = 8.68m, Bid = 19.9m, OfferPrice = 100m, BidPrice = 20m},
    new Auction {GroupId = 2, Date = DateTime.Parse("27/06/2013"), Hour = "01:45", Offer = 0m, Bid = 0m, OfferPrice = 250m, BidPrice = 20m},
    new Auction {GroupId = 2, Date = DateTime.Parse("27/06/2013"), Hour = "02:00", Offer = 8.68m, Bid = 19.9m, OfferPrice = 100m, BidPrice = 20m},
    new Auction {GroupId = 2, Date = DateTime.Parse("27/06/2013"), Hour = "02:15", Offer = 0m, Bid = 0m, OfferPrice = 100m, BidPrice = 20m},
    new Auction {GroupId = 2, Date = DateTime.Parse("27/06/2013"), Hour = "02:30", Offer = 8.68m, Bid = 19.9m, OfferPrice = 100m, BidPrice = 20m},
    new Auction {GroupId = 2, Date = DateTime.Parse("27/06/2013"), Hour = "02:45", Offer = 0m, Bid = 0m, OfferPrice = 100m, BidPrice = 20m},
    new Auction {GroupId = 2, Date = DateTime.Parse("27/06/2013"), Hour = "03:00", Offer = 8.68m, Bid = 19.9m, OfferPrice = 100m, BidPrice = 20m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "03:15", Offer = 87.14m, Bid = 87.1m, OfferPrice = 150m, BidPrice = 0m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "03:30", Offer = 0m, Bid = 0m, OfferPrice = 150m, BidPrice = 0m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "03:45", Offer = 0m, Bid = 0m, OfferPrice = 150m, BidPrice = 0m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "04:00", Offer = 0m, Bid = 0m, OfferPrice = 150m, BidPrice = 0m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "04:15", Offer = 0m, Bid = 0m, OfferPrice = 150m, BidPrice = 0m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "04:30", Offer = 0m, Bid = 0m, OfferPrice = 150m, BidPrice = 0m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "04:45", Offer = 0m, Bid = 0m, OfferPrice = 150m, BidPrice = 0m},
    new Auction {GroupId = 3, Date = DateTime.Parse("27/06/2013"), Hour = "05:00", Offer = 0m, Bid = 0m, OfferPrice = 150m, BidPrice = 0m}
};

// Create 2 BOD object for each Auction
var b1 =
        from a in auctions
        from b in new List<BOD> {
                new BOD { Date = a.Date, Time = a.Hour, Price = a.BidPrice, Volume = a.Bid },
                new BOD { Date = a.Date, Time = a.Hour, Price = a.OfferPrice, Volume = a.Offer } 
        }
        select b;

// Create 2 BOD object with zero price and volume for each Auction with another GroupId
var b2 =
        from d in auctions.Select(x => x.GroupId)
        from a in auctions.Where(y => y.GroupId != d)
        from b in new List<BOD> {
                new BOD { Date = a.Date, Time = a.Hour, Price = 0, Volume = 0 },
                new BOD { Date = a.Date, Time = a.Hour, Price = 0, Volume = 0 } 
        }
        select b;

var bods = b1.Union(b2);

【讨论】：