Linq计算时间差并选择最接近的时间差

Question

我有这样一个对象列表：

+-------------+------------+---------------------+
| ID          | Value      | Time                | 
+-------------+------------+---------------------+
| 1           | 1          | 2019-03-07 20:05:35 |
| 2           | 2          | 2019-03-07 20:06:09 |  
| 5           | 5          | 2019-03-07 20:11:27 |
| 7           | 1          | 2019-03-07 20:13:30 |
| 8           | 0          | 2019-03-07 20:13:41 |
| 7           | 1          | 2019-03-07 20:17:00 |
| 8           | 0          | 2019-03-07 20:22:20 |
| 7           | 1          | 2019-03-07 20:23:05 |
| 8           | 0          | 2019-03-07 20:27:35 |
| 7           | 1          | 2019-03-07 20:27:37 |
| 8           | 0          | 2019-03-07 20:28:01 |
| 7           | 1          | 2019-03-07 20:37:19 |
| 8           | 0          | 2019-03-07 20:37:27 |
| 7           | 1          | 2019-03-07 20:37:54 |
| 8           | 0          | 2019-03-07 20:40:11 |
| 7           | 1          | 2019-03-07 20:44:00 |
| 8           | 0          | 2019-03-07 20:45:00 |
| 7           | 1          | 2019-03-07 20:47:41 |
| 7           | 1          | 2019-03-07 20:48:43 |
| 7           | 1          | 2019-03-07 20:48:51 |
| 8           | 0          | 2019-03-07 20:51:11 |
| 8           | 0          | 2019-03-07 20:54:46 |
| 8           | 0          | 2019-03-07 20:55:36 |
+-------------+------------+---------------------+

如何select记录相隔15分钟但记录更接近下一次的时间？

结果应该是这样的：

+-------------+------------+---------------------+
| ID          | Value      | Time                | 
+-------------+------------+---------------------+
| 1           | 1          | 2019-03-07 20:05:35 |
| 8           | 0          | 2019-03-07 20:22:20 |
| 7           | 1          | 2019-03-07 20:37:19 |
| 8           | 0          | 2019-03-07 20:51:11 |
+-------------+------------+---------------------+

如果第一次是 20:05:35，接下来间隔 15 分钟是 20:22:20。最接近的时间是 20:22:20，因为它们之间的差异是 00:02:14，而 20:17:35 之间的差异是 00:02:25。有什么方法可以计算出差异并决定选择哪个更接近？

Answer 1

尝试以下操作：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ConsoleApplication132
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Dates> dates = Dates.GetDates();

            var results = dates.GroupBy(x => new DateTime(x.Time.Year, x.Time.Month, x.Time.Day, x.Time.Hour, 15 * (x.Time.Minute / 15), 0).AddMinutes(15))
                .Select(x => x.OrderBy(y => x.Key.Subtract(y.Time)).First())
                .ToList();
        }
    }
    public class Dates
    {
        public int ID { get;set;}
        public int Value { get;set;}
        public DateTime Time { get;set;}

        public static List<Dates> GetDates()
        {
            string input =
                "| 1           | 1          | 2019-03-07 20:05:35 |\n" +
                "| 2           | 2          | 2019-03-07 20:06:09 |\n" +
                "| 5           | 5          | 2019-03-07 20:11:27 |\n" +
                "| 7           | 1          | 2019-03-07 20:13:30 |\n" +
                "| 8           | 0          | 2019-03-07 20:13:41 |\n" +
                "| 7           | 1          | 2019-03-07 20:17:00 |\n" +
                "| 8           | 0          | 2019-03-07 20:22:20 |\n" +
                "| 7           | 1          | 2019-03-07 20:23:05 |\n" +
                "| 8           | 0          | 2019-03-07 20:27:35 |\n" +
                "| 7           | 1          | 2019-03-07 20:27:37 |\n" +
                "| 8           | 0          | 2019-03-07 20:28:01 |\n" +
                "| 7           | 1          | 2019-03-07 20:37:19 |\n" +
                "| 8           | 0          | 2019-03-07 20:37:27 |\n" +
                "| 7           | 1          | 2019-03-07 20:37:54 |\n" +
                "| 8           | 0          | 2019-03-07 20:40:11 |\n" +
                "| 7           | 1          | 2019-03-07 20:44:00 |\n" +
                "| 8           | 0          | 2019-03-07 20:45:00 |\n" +
                "| 7           | 1          | 2019-03-07 20:47:41 |\n" +
                "| 7           | 1          | 2019-03-07 20:48:43 |\n" +
                "| 7           | 1          | 2019-03-07 20:48:51 |\n" +
                "| 8           | 0          | 2019-03-07 20:51:11 |\n" +
                "| 8           | 0          | 2019-03-07 20:54:46 |\n" +
                "| 8           | 0          | 2019-03-07 20:55:36";
            List<Dates> dates = new List<Dates>();

            string line = "";
            StringReader reader = new StringReader(input);

            while ((line = reader.ReadLine()) != null)
            {
                string[] lineArray = line.Split(new char[] { '|' }, StringSplitOptions.RemoveEmptyEntries);

                Dates newDate = new Dates()
                {
                    ID = int.Parse(lineArray[0]),
                    Value = int.Parse(lineArray[1]),
                    Time = DateTime.Parse(lineArray[2])
                };

                dates.Add(newDate);
            }
            return dates;
        }
    }

}

代码将时间精确地移动到下一个间隔的 15 分钟间隔。时间的最小分辨率是 100ns（1 个滴答声）所以减去 1 个滴答声我认为是正确的解决方案

            var results = dates.GroupBy(x => new DateTime(x.Time.Year, x.Time.Month, x.Time.Day, x.Time.Hour, 15 * (x.Time.Minute / 15), 0).AddMinutes(15).AddTicks(-1))
                .Select(x => x.OrderBy(y => x.Key.Subtract(y.Time)).First())
                .ToList();

要从开始时间开始按 15 分钟分组，请使用此

            //tick is 100ns
            const long TICKS_PER_15_MINUTES = 15 * 60 * 10000000L; //minutes, seconds, ticks 

            DateTime minTime = dates.OrderBy(x => x.Time).First().Time;

            List<Dates> results = dates.GroupBy(x => (TICKS_PER_15_MINUTES * ((x.Time.Ticks - minTime.Ticks) / TICKS_PER_15_MINUTES) + TICKS_PER_15_MINUTES - 1))
                .Select(x => x.OrderBy(y => x.Key - y.Time.Ticks).First())
                .ToList();

最后，如果你想离最短时间最近 15 分钟

            //tick is 100ns
            const long TICKS_PER_15_MINUTES = 15 * 60 * 10000000L; //minutes, seconds, ticks 

            DateTime minTime = dates.OrderBy(x => x.Time).First().Time;

            List<Dates> results = dates.GroupBy(x => ((x.Time.Ticks - minTime.Ticks) % TICKS_PER_15_MINUTES) < (TICKS_PER_15_MINUTES / 2)
                ? TICKS_PER_15_MINUTES * ((x.Time.Ticks - minTime.Ticks) / TICKS_PER_15_MINUTES)
                : (TICKS_PER_15_MINUTES * ((x.Time.Ticks - minTime.Ticks) / TICKS_PER_15_MINUTES)) + TICKS_PER_15_MINUTES)
                .Select(x => x.OrderBy(y => Math.Abs( x.Key - y.Time.Ticks)).First())
                .ToList();

Linq计算时间差并选择最接近的时间差

Linq caculate time difference and choose closest one

c#

linq

datediff