Question

我有如下用法集合，需要如下输出：

这是我的用法类：

public class Usage
{
    public Usage()  {}
    public string Alias { get; set; }
    public int ActivityCount { get; set; }
    public DateTime HitDate { get; set; }

}

这是我的代码：

我想首先将集合分组到用户中，对于每个用户，我想获得每天的点击次数，如下面的EXPECTED输出所示。请注意，日期时间a和d在同一天是不同的时间，因此需要将它们组合在一起。

这将用于绘制命中与日期的条形图，即每天的命中数

执行此操作时，我无法将别名字段数据保存到我的第二级分组中：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace NullOperator
{
    class Program
{
    static void Main(string[] args)
    {
        var a = new DateTime(2015, 10, 23, 12, 05, 06);
        var b = new DateTime(2015, 10, 24, 12, 05, 06);
        var c = new DateTime(2015, 10, 25, 12, 05, 06);
        var d = new DateTime(2015, 10, 23, 14, 05, 06);

        var usages = new List<Usage>
        {
            new Usage{Alias = "A ",HitDate = a},
            new Usage{Alias = "A ",HitDate = a},
            new Usage{Alias = "A ",HitDate = d},
            new Usage{Alias = "A ",HitDate = b},
            new Usage{Alias = "A ",HitDate = b},
            new Usage{Alias = "A ",HitDate = b},
            new Usage{Alias = "A ",HitDate = c},


            new Usage{Alias = "B ",HitDate = a},
            new Usage{Alias = "B ",HitDate = b},
            new Usage{Alias = "B ",HitDate = b},
            new Usage{Alias = "B ",HitDate = c},
            new Usage{Alias = "B ",HitDate = c},
            new Usage{Alias = "B ",HitDate = c},

            new Usage{Alias = "C ",HitDate = a},
            new Usage{Alias = "C ",HitDate = a},
            new Usage{Alias = "C ",HitDate = a},
            new Usage{Alias = "C ",HitDate = c},
            new Usage{Alias = "C ",HitDate = c},
            new Usage{Alias = "C ",HitDate = c},
        };

        var g = usages.GroupBy(r => r.Alias);

        foreach (var u in g)
        {          
            var x = u.GroupBy(r => r.HitDate.Day).Select(gr=>new
            {
                HitDate=gr.Key,
                Count=gr.Count()
            });

            foreach (var m in x)
            {
                Console.WriteLine(m.HitDate + "  " +m.Count);
            }
        }

        Console.Read();
    }
}

//预期输出

Alias : HitDate.Date  : hitcount
//  A  - 23/10/2015  - 3
//  A  - 24/10/2015 - 3
//  A  - 25/10/2015 - 1

//  B  - 23/10/2015 - 1
//  B  - 24/10/2015 - 2
//  B  - 25/10/2015 - 3

//  C  - 23/10/2015 - 3
//  C  - 24/10/2015- 0
//  C - 25/10/2015 -  3

获得的输出：

正如您所看到的，分组是正常的，但是整个Date和Alias等信息会丢失，并且无法在嵌套循环的代码中检索它们。

对此有何建议？关于如何获得所需的输出？

Answer 1

基本上这里有两个问题：

您按Day分组，而不是Date，我怀疑您要做
你没有使用你已经将别名作为外部分组中的键的事实

实际上，您可以通过一次性按别名和日期分组来更简单地执行此操作：

var query = usages.GroupBy(r => new { r.Alias, r.HitDate.Date },
                           (key, elements) => new { key.Alias,
                                                    key.Date,
                                                    Count = elements.Count() })
                  .OrderBy(x => x.Alias)
                  .ThenBy(x => x.Date);

foreach (var item in query)
{
    Console.WriteLine("{0} {1} {2}", item.Alias, item.Date, item.Count);
}

Answer 2

您也可以在select语句中选择该值。

var g = usages.GroupBy(r => r.Alias); 
foreach (var u in g) 
{ 
    var x = u.GroupBy(r => r.HitDate.Day)
             .Select(gr => new { 
                                   Alias=u.Alias,
                                   HitDate=gr.Key, 
                                   Count=gr.Count() 
             }); 
    foreach (var m in x) 
    {
        Console.WriteLine(m.HitDate + " " + m.Count); 
    } 
}

由linq

2 个答案: