合并类单一清单

Question

我有一个类列表，其中包含事件名称、时间戳和持续时间（timespan）。有许多重复的事件名称。我想通过事件名称合并它们，并添加它们的持续时间，并保留最早的时间戳，除非事件具有特定的名称。即,删除重复的事件名称,为相似的事件名称添加持续时间,并保留偶数名称的最早时间戳。

有更好的方法吗？可能是用LINQ吗？

下面是我尝试过的，它似乎没有正确地合并（仍然有重复的但更少）

类：

public class eventRecords
{
    public DateTime TimeStamp { get; set; }
    public string Event { get; set; }
    public TimeSpan Duration { get; set; }
}  

我的尝试：

// allEventList is already sorted by TimeStamp, so my thinking is adding
// the first occurrence of an event to newList will keep the earliest
// TimeStamp in eventRecrods for that event
// Also - the duplicates are almost all consecutive in allEventList

var newList = new List<eventRecords>();
for (int ii = 0; ii < allEventList.Count; ii++ )
{
    newList.Add(allEventList[ii]);
    if((ii + 1) < allEventList.Count && allEventList[ii] != keyword)
    {
        if(allEventList[ii].Event == allEventList[ii+1].Event)
        {
            newList.Last().Duration = newList.Last().Duration+ allEventList[ii + 1].Duration; 
            ii = ii + 1;
        }

    }

}

例如，如果allEventList包含：

Event = "Action 1", TimeStamp = 08:00, Duration = TimeSpan.FromMinutes(1);
Event = "Action 1", TimeStamp = 09:00, Duration = TimeSpan.FromMinutes(1);
Event = "Action 1", TimeStamp = 10:00, Duration = TimeSpan.FromMinutes(1);
Event = "KeyWord", TimeStamp = 11:00, Duration = TimeSpan.FromMinutes(1);
Event = "Action 2", TimeStamp = 12:00, Duration = TimeSpan.FromMinutes(1);
Event = "Action 2", TimeStamp = 13:00, Duration = TimeSpan.FromMinutes(1);

newList应包含：

Event = "Action 1", TimeStamp = 08:00, Duration = TimeSpan.FromMinutes(3);
Event = "KeyWord", TimeStamp = 11:00, Duration = TimeSpan.FromMinutes(1);
Event = "Action 2", TimeStamp = 12:00, Duration = TimeSpan.FromMinutes(2);

Answer 1

这一点相当容易

我想按事件名称合并它们，并添加它们的持续时间，并保留最早的时间戳

allEventList.GroupBy(e => e.Event)
        .Select(g => new eventRecords{
             TimeStamp = g.Min(e => e.TimeStamp),
             Event = g.Key,
             Duration = new TimeSpan(g.Sum(e => e.Duration.Ticks))
         });

这是通过首先按event对列表进行分组来实现的，这给出了一个IEnumerable > 。然后使用select投影这些组，以生成一个新的EventRecords并根据请求聚合所需属性。

现场示例：http://rextester.com/mtvnh46675

作为对您的评论的答复，您可以在使用where对列表进行分组之前对其进行筛选。例如，如果您只需要事件名称长度大于5的事件（虚构的示例！）

allEventList.Where(e => e.Event.Length>5)
            .GroupBy(e => e.Event)
            .... etc