CODEWITHSUNDEEP
c#linq
Josef
Josef

Reputation: 2726

LINQ: Extract data every X minutes

Here is piece of code which creates random data with different datetime.

void ExtractEveryXminute()
{
     List<DataHolder> data = new List<DataHolder>();
     List<DateTime> randomTimes = new List<DateTime>();
     Random r = new Random();
     DateTime d = new DateTime(2019, 9, 19, 7, 0, 0);

     for (int i = 0; i < 100; i++)
     {
         DataHolder dh = new DataHolder();
         TimeSpan t = TimeSpan.FromSeconds(r.Next(0, 14400));  
         dh.OID = i;
         dh.Value = r.Next(50);
         dh.Snapshottime = d.Add(t);

         data.Add(dh);
      }

      data.OrderBy(o => o.Snapshottime).ToList();

      List<DataHolder> SortedList = data.OrderBy(o => o.Snapshottime).ToList();           

      var query_res = (from s in SortedList group s by new DateTime(s.Snapshottime.Year, s.Snapshottime.Month, s.Snapshottime.Day, s.Snapshottime.Hour, 15, 0));
}

public class DataHolder
{
    public int OID { get; set; }
    public double Value { get; set; }
    public DateTime Snapshottime { get; set; }       
}

I need to get data apart let's say every 15 minutes. Now I'm getting only datetime at 07:15:00, 8:15:00, 9:15:00 but this is not correct. How to extract those date starting from first record in list and filter every 15 minutes?

Upvotes: 1

Views: 847

Answers (1)

Anu Viswan
Anu Viswan

Reputation: 18155

You could use the following.

TimeSpan interval = new TimeSpan(0, 15, 0); 
var result = SortedList.GroupBy(x=> x.Snapshottime.Ticks/interval.Ticks)
                       .OrderBy(x=>x.Key);

Sample Output

enter image description here

Update

If, as per the comment, you want only the first time from each group of 15 min interval, then you could use.

var result = SortedList.GroupBy(x=> x.Snapshottime.Ticks/interval.Ticks)
                       .Select(x=>x.First());

Upvotes: 3

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