根據屬性c＃拆分對象列表

Question

myClass結構：

public class myClass
    {
        public string Name { get; set; }
        public string AdditionalData { get; set; }
        public System.DateTime ActivityTime { get; set; }
    }

我有一個以上類List<myClass>的列表，所有這些List<myClass>均由ActivityTime排序。

我需要拆分上面的列表，並獲取List<List<myClass>>這樣，如果兩個連續的ActivityTime之間的差異超過特定時間段（例如5分鍾），我希望拆分發生。

真誠的感謝您的幫助。

謝謝

Answer 1

那這個解決方案呢 ：

var data = new List<myClass> {
    new myClass { ActivityTime = new DateTime(2016, 01, 01, 01, 00, 00) },
    new myClass { ActivityTime = new DateTime(2016, 01, 01, 01, 05, 00) },
    new myClass { ActivityTime = new DateTime(2016, 01, 01, 01, 06, 00) },
    new myClass { ActivityTime = new DateTime(2016, 01, 01, 01, 07, 00) },
    new myClass { ActivityTime = new DateTime(2016, 01, 01, 01, 17, 00) }
};

var period = 5;
var firstActivityTime = data.Min(x => x.ActivityTime);
var answer = data.OrderBy(x => x.ActivityTime).GroupBy(x => {
        var dif = (x.ActivityTime - firstActivityTime).Minutes;
        return dif / period - (dif % period == 0 && dif / period != 0 ? 1 : 0);
    }).Select(x => x.ToList()).ToList();

Answer 2

您可以通過簡單的迭代來做到這一點：

var myList = new List<myClass>()
{
    new myClass() { Name = "ABC", AdditionalData = "1", ActivityTime = DateTime.Now },
    new myClass() { Name = "ABC2", AdditionalData = "2", ActivityTime = DateTime.Now },
    new myClass() { Name = "ABC3", AdditionalData = "3", ActivityTime = DateTime.Now.AddSeconds(6) },
    new myClass() { Name = "ABC4", AdditionalData = "3", ActivityTime = DateTime.Now.AddSeconds(11) },
    new myClass() { Name = "ABC4", AdditionalData = "3", ActivityTime = DateTime.Now.AddSeconds(12) }
};

var results = new List<List<myClass>>();

myClass previousItem = null;
List<myClass> currentList = new List<myClass>();
foreach (var item in myList)
{
    if (previousItem == null || (item.ActivityTime - previousItem.ActivityTime).TotalSeconds >= 5)
    {
        currentList = new List<myClass>();
        results.Add(currentList);
    }

    currentList.Add(item);
    previousItem = item;
}

Answer 3

可以實現多種方法，但是基本原理是相同的。 處理第n(th)元素時，請跟蹤第n-1個元素，並計算這兩個元素之間的timespan 。

你可以做這樣的事情。

List<MyClass> data = ...; // input
int gid=0;
DateTime prevvalue = data[0].ActivityTime;                          // Initial value 

var result =  data.Select(x=>
{
    var obj =  x.ActivityTime.Subtract(prevvalue).TotalMinutes<5?  // Look for timespan difference
                 new {gid= gid, item =x}                          // Create groups based on consecutive gaps. 
                :new {gid= ++gid, item =x};
    prevvalue= x.ActivityTime;                                      // Keep track of previous value (for next element process)
    return obj;
})
.GroupBy(x=>x.gid)                                                  // Split into groups 
.Select(x=>x.Select(s=>s.item).ToList())
.ToList();

檢查這個Demo