如何将对象列表拆分为按元素（日期时间和字符串）分组的子列表 C#

Question

我正在尝试根据日期时间升序基于包含 9 条记录的主列表制作子列表，然后是 pcName(string)。

我的排序子列表需要如下所示

对象列表 1 :

2615,2019-11-22 16:03:22.150,Test1

2615,2019-11-22 16:03:22.200,Test1

2615,2019-11-22 16:03:22.250,Test1

2615,2019-11-22 16:03:22.300,Test1

对象列表 2 :

2615,2019-11-22 16:03:22.350,Test2

2615,2019-11-22 16:03:22.400,Test2

对象列表 3 :

2615,2019-11-22 16:03:22.450,Test1

2615,2019-11-22 16:03:22.500,Test1

对象列表 4 :

2615,2019-11-22 16:03:22.550,Test3

这个对象列表需要按照ObjectList[0],ObjectList[1],ObjectList[2],ObjectList[3]的顺序取

我在下面提到了我的示例代码

但这只为我提供了 3 个基于 Test1、Test2 和 Test3 的子列表集（Item1）过滤器和 9 个子列表，但我想要上述 4 个子列表。我想在哪里更改代码？？ 请帮帮我

private void button_Click(object sender, EventArgs e)
        {
            List<Identity> listOfIdentity = new List<Identity>()
            {
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.550"),PcName="Test3"},                              
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.300"), PcName="Test1"},                            
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.350"), PcName="Test2"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.400"), PcName="Test2"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.200"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.500"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.250"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.450"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.150"), PcName="Test1"}              
            };
            List<Identity> sortedIdentity = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).ToList(); // here i order by time and then pc name

            var items1 = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).GroupBy(x => x.PcName).Select(grp => grp.ToList()).ToList(); //sub list create based with **Test1, Test2 & Test3** (3 sub lists)
            var items2 = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).GroupBy(x => new { x.QCTime, x.PcName }).Select(grp => grp.ToList()).ToList(); //sub list create based with each time and pc name (9 sublists)
        }

        class Identity
        {
            public int id { get; set; }
            public DateTime QCTime { get; set; }
            public string PcName { get; set; }
        }

Answer 1

由于您尝试按 DateTime 列进行分组，并且该列仅以毫秒为单位变化，因此分组没有按照您的预期进行。我修改了你的代码如下：

class Identity
    {
        public int id { get; set; }
        public DateTime QCTime { get; set; }
        public string PcName { get; set; }

        public string QCTimeForGroup
        {
            get
            {
                if (QCTime.Millisecond <= 300)
                {
                    return "SL1";
                }
                else if (QCTime.Millisecond > 300 && QCTime.Millisecond <= 400)
                {
                    return "SL2";
                }
                else if (QCTime.Millisecond > 400 && QCTime.Millisecond <= 500)
                {
                    return "SL3";
                }

                return "SL4";
            }
        }
    }


private void button_Click(object sender, EventArgs e)
        {
            List<Identity> listOfIdentity = new List<Identity>()
            {
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.550"),PcName="Test3"},                              
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.300"), PcName="Test1"},                            
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.350"), PcName="Test2"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.400"), PcName="Test2"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.200"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.500"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.250"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.450"), PcName="Test1"},
               new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.150"), PcName="Test1"}              
            };
            List<Identity> sortedIdentity = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).ToList(); // here i order by time and then pc name

            var items1 = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).GroupBy(x => x.PcName).Select(grp => grp.ToList()).ToList(); //sub list create based with **Test1, Test2 & Test3** (3 sub lists)
            var items2 = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).GroupBy(x => new { x.QCTime, x.PcName }).Select(grp => grp.ToList()).ToList(); //sub list create based with each time and pc name (9 sublists)
            var items3 = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName)
                        .GroupBy(x => new { x.QCTimeForGroup, x.PcName }).Select(grp 
                        => grp.ToList()).ToList(); 
        }

Answer 2

这是我使用 Linq.Aggregate 的解决方案：

private void button_Click(object sender, EventArgs e)
{
    List<Identity> listOfIdentity = new List<Identity>()
    {
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.550"), PcName="Test3"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.300"), PcName="Test1"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.350"), PcName="Test2"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.400"), PcName="Test2"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.200"), PcName="Test1"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.500"), PcName="Test1"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.250"), PcName="Test1"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.450"), PcName="Test1"},
        new Identity() {id= 2615,QCTime=DateTime.Parse("2019-11-22 16:03:22.150"), PcName="Test1"}
    };
    List<Identity> sortedIdentity = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).ToList(); // here i order by time and then pc name
    var result = sortedIdentity.Skip(1).Aggregate(new List<List<Identity>> { new List<Identity> { sortedIdentity[0] } }, (lists, curr) =>
    {
        if (curr.PcName == lists.Last()[0].PcName)
            lists.Last().Add(curr);
        else
            lists.Add(new List<Identity> { curr });
        return lists;
    });
}

它遍历每个元素并检查它的 PcName 是否与之前的相同。如果是，则它在同一个列表中，否则使用此元素创建新列表。

编辑：Matt.G

建议的更优雅的解决方案

    List<Identity> sortedIdentity = listOfIdentity.OrderBy(x => x.QCTime).ThenBy(x => x.PcName).ToList();
    var result = sortedIdentity.Aggregate(new List<List<Identity>>(), (lists, curr) => 
   { 
        if (curr.PcName == lists.LastOrDefault()?.FirstOrDefault()?.PcName)
            lists.Last().Add(curr);
        else
            lists.Add(new List<Identity> { curr });
        return lists;
    });

Answer 3

没有专门用于一次性对连续元素进行分组的内置 LINQ 方法。创建一个并不难。一个实现可以在中找到，签名如下：

public static IEnumerable<IEnumerable<TSource>> SplitByPredicate<TSource>(
    this IEnumerable<TSource> source,
    Func<TSource, TSource, bool> splitPredicate);

您可以像这样使用它来解决您的问题：

var sublists = listOfIdentity
    .OrderBy(x => x.QCTime)
    .ThenBy(x => x.PcName)
    .SplitByPredicate((x, y) => x.PcName != y.PcName);

可以找到不同的实现，其签名略有不同：

public static IEnumerable<List<TSource>> GroupConsecutiveByKey<TSource, TKey>(
    this IEnumerable<TSource> source,
    Func<TSource, TKey> keySelector);

...可以这样使用：

var sublists = listOfIdentity
    .OrderBy(x => x.QCTime)
    .ThenBy(x => x.PcName)
    .GroupConsecutiveByKey(x => x.PcName);

如何将对象列表拆分为按元素（日期时间和字符串）分组的子列表 C#

How to Split a object list into sublists grouping by elements(dateTime and String) C#

c#

linq

tobjectlist

sublist