c# - Linq Groupby Sum 一个嵌套的可观察集合

Question

我需要一些帮助来汇总我收藏中的数据。

RrvResponse 类

/// <summary>
    /// The RRV response.
    /// </summary>
    public class RrvResponse
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="RrvResponse"/> class.
        /// </summary>
        public RrvResponse()
        {
            this.BoDPoints = new ObservableCollection<BidOfferPoint>();    
        }

        /// <summary>
        /// Gets or sets the id.
        /// </summary>
        public string Id { get; set; }

        /// <summary>
        /// Gets or sets the message date.
        /// </summary>
        public DateTime MessageDate { get; set; }

        /// <summary>
        /// Gets or sets the BOD points.
        /// </summary>
        public ObservableCollection<BidOfferPoint> BoDPoints { get; set; }
    }

实现，

var responses = new ObservableCollection<RrvResponse>();

// ....Load responses...
// ...
// ...

响应的数量是 5，所以我在响应中有 5 个 BoDPoints 的 ObservableCollection。

BOD points are,

    /// <summary>
        /// The bid offer point.
        /// </summary>
        public class BidOfferPoint
        {

            /// <summary>
            /// Gets or sets the date.
            /// </summary>
            public DateTime Date { get; set; }

            /// <summary>
            /// Gets or sets the time.
            /// </summary>
            public string Time { get; set; }

            /// <summary>
            /// Gets or sets the volume.
            /// </summary>
            public decimal Volume { get; set; }

            /// <summary>
            /// Gets or sets the price.
            /// </summary>
            public decimal Price { get; set; }
        }

示例，

Observable Collection Bod - 1
2013-06-21 
00:00
100
10

2013-06-21
00:15
120
15

2013-06-21
00:30
150
9

可观察集合 Bod - 2

2013-06-21 
00:00
Observable Collection Bod - 1
2013-06-21 
00:00
100
10

2013-06-21
00:15
120
15

2013-06-21
00:30
150
9
40
1

2013-06-21
00:15
10
0.5

2013-06-21
00:30
11
0.1

Observable 集合 Bod - 3

2013-06-15 
00:00
100
10

2013-06-15
00:15
120
15

2013-06-15
00:30
150
9

我想按日期分组，然后按时间分组，然后合计卷数。因此，在上面的示例中，应汇总 2013 年 6 月 21 日 00:00 的所有交易量，应汇总 2013 年 6 月 21 日 00:15 的所有交易量。

使用 Linq 执行此操作的最佳方法是什么？

Answer 1

您可以使用SelectMany 聚合项目并在之后对它们进行分组:

var result = responses
    .SelectMany(r => r.BoDPoints)
    .GroupBy(p => p.Date)
    .Select(byDate => 
        new 
        {
            Date = byDate.Key,
            EntriesByTime = byDate
                .GroupBy(p => p.Time)
                .Select(byTime => 
                    new 
                    {
                        Time = byTime.Key,
                        TotalVolume = byTime.Sum(p => p.Volume)
                    })
        });

您可以使用以下循环(例如输出总音量)

foreach (var byDate in result)
{
    Console.WriteLine("Entries for date " + byDate.Date);
    foreach (var byTime in byDate.EntriesByTime)
    {
        Console.WriteLine("Total volume for time " + byTime.Time + ": " + byTime.TotalVolume);
    }
}