C＃从linq组中的日期获取分钟数

Question

我需要按一天中的每一分钟对我的数据进行分组，并获取在那一分钟内发生的事件的计数。我目前有：

                items.GroupBy(x => new
                {
                    x.date.Minute,
                    x.date.Hour
                })
                .Select(x => new TransferObject
                {
                    Minute = x.Key.Minute,
                    Hour = x.Key.Hour,
                    Count = x.Count(),
                    Day = date
                }).OrderBy(x => x.Hour).ThenBy(x => x.Minute).ToList();

这满足了我的需要，但问题是我可能没有每一分钟的数据点，如果我没有那一分钟的数据，我如何向 Count 字段添加 0？或者我可以添加分钟数 (0...1440) 并稍后添加缺失值。

编辑

解决方案目前仅按开始日期分组，但该对象实际上有一个字段 end_date。所以基本上现在我有在那一分钟开始的所有事件，但我需要得到那一分钟运行的事件数。

我拥有的数据包含：

date                    end_date
2015-05-15 09:52:15.650 2015-05-15 09:55:38.097
2015-05-15 09:52:15.633 2015-05-15 09:52:16.097
2015-05-15 09:52:11.633 2015-05-15 09:52:13.047
2015-05-15 09:51:49.097 2015-05-15 09:55:17.687
2015-05-15 09:51:49.087 2015-05-15 09:56:17.510

目前它不使用 end_date 字段所以输出是

{Count:2;Hour:9;Minute:51}  
{Count:3;Hour:9;Minute:52}

我需要所有运行的事件，比如

{Count:2;Hour:9;Minute:51}  
{Count:5;Hour:9;Minute:52}
{Count:3;Hour:9;Minute:53}
{Count:3;Hour:9;Minute:54}
{Count:3;Hour:9;Minute:55}
{Count:2;Hour:9;Minute:56}

Answer 1

看来，您想要 GroupJoin() 而不仅仅是 GroupBy()，类似这样的东西：

  var source = ... // Your query;

  var result = Enumerable
    .Range(0, 1440) // All the minutes that should be in the result
    .GroupJoin(source, 
       minutes => minutes, 
       item => item.Hour * 60 + item.Minute,
       (minutes, items) => new {
          hour = minutes / 60,
          minute = minutes % 60,
          count = items.Count() } ); // Count() can well return 0...

Answer 2

这应该可以在没有任何 join 的情况下工作。假设项目中只有一个日期。

var date = items.Select(i => i.date).Min();

Enumerable.Range(0, 60 * 24)
.Select(i => 
    new 
    {
        Minute = i % 60, 
        Hour = i / 60, 
        Day = date,
        Count = items.Where(j => j.date.Hour = i / 60 && j.date.Minute = i % 60).Count()
    });

Answer 3

首先，您可以使用一些简单的 LINQ 生成一天中的所有小时和分钟：

var all = Enumerable.Range(0,24)
                    .SelectMany(x => Enumerable.Range(0,60),
                                (x,y) => new {Hr = x, Min=y});
foreach(var a in all)
    Console.WriteLine("{0}:{1}",a.Hr,a.Min); // 00:00 thru 23:59

实例：http://rextester.com/NPNKN82691

然后您可以使用此集合加入您的原始结果以形成最终输出：

var all = Enumerable.Range(0,24)
                    .SelectMany(x => Enumerable.Range(0,60),
                               (x,y) => new {Hr = x, Min=y});

var items = new[]{
        new Item{Date = new DateTime(2015,01,01,0,1,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0)},
        new Item{Date = new DateTime(2015,01,01,0,3,0)}
};

var results = all.GroupJoin(items,
                            x => new {Hour = x.Hr,Minute = x.Min},
                            y => new {Hour = y.Date.Hour,Minute = y.Date.Minute},
                            (x,y) => new {Hour = x.Hr, Minute = x.Min, Count = y.Count()});

foreach(var result in results)
   Console.WriteLine("{0:00}:{1:00} = {2}",result.Hour, result.Minute, result.Count);

输出

00:00 = 0
00:01 = 6
00:02 = 0
00:03 = 1
00:04 = 0
//..snip..//
23:55 = 0
23:56 = 0
23:57 = 0
23:58 = 0
23:59 = 0

实例http://rextester.com/OAYZ95244

编辑

考虑到您考虑范围日期的要求更改，您可以添加一个新的 class 和用于从每个项目推断小时和分钟的方法：

 // classes used
 public class ExtrapolatedItem
 {
     public int Hour{get;set;}
     public int Minute{get;set;}
 }

public class Item{
    public DateTime Date{get;set;}
    public DateTime EndDate{get;set;}
}

// method 

private static IEnumerable<ExtrapolatedItem> Extrapolate(Item item)
{
    for(var d = item.Date;d<=item.EndDate; d = d.AddMinutes(1))
    {
        yield return new ExtrapolatedItem{ Hour = d.Hour, Minute = d.Minute};
    }
}

然后可以像这样在原始方法中使用：

var items = new[]{
        new Item{Date = new DateTime(2015,01,01,0,1,0),EndDate = new DateTime(2015,1,1,0,5,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0),EndDate = new DateTime(2015,1,1,0,5,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0),EndDate = new DateTime(2015,1,1,0,5,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0),EndDate = new DateTime(2015,1,1,0,5,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0),EndDate = new DateTime(2015,1,1,0,5,0)},
        new Item{Date = new DateTime(2015,01,01,0,1,0),EndDate = new DateTime(2015,1,1,0,5,0)},
        new Item{Date = new DateTime(2015,01,01,0,3,0),EndDate = new DateTime(2015,1,1,0,5,0)}
};
var results = all.GroupJoin(items.SelectMany(Extrapolate), // extrapolate each item to a list of extrapolated items
                            x => new {Hour = x.Hr,Minute = x.Min},
                            y => new {Hour = y.Hour,Minute = y.Minute},
                            (x,y) => new {Hour = x.Hr, Minute = x.Min, Count = y.Count()});

输出

00:00 = 0
00:01 = 6
00:02 = 6
00:03 = 7
00:04 = 7
00:05 = 7
00:06 = 0
00:07 = 0
//..snip..//

实例：http://rextester.com/VOVJCS56741

C＃从linq组中的日期获取分钟数

C# get minute number from date in linq group by

c#

linq

datetime

group-by

编辑