Question

I have a LINQ query that is currently like this:

var query = from l in Records
            where l.time >= time1 && l.time <= time2
            select l;

however, the Records collection used to log once every two seconds, now it logs once an hour. I need a way of only grabbing one Record an hour from the old data, so that the returned data makes more sense, and so I don’t return months of data logged every 2 seconds…Any help would be great.

Answer 1

So you want only one record per hour. That means you need to group by hour:

var query = records
            .Where(r => r.time >= time1 && r.time <= time2)
            .Select(r => new
            {
                Hour = new DateTime(r.time.Year, r.time.Month, r.time.Day, r.time.Hour, 0, 0),
                Record = r
            })
            .GroupBy(x => x.Hour)
            .Select(grp => grp.First().Record);