Question

I’m not a super expert on LINQ, I’ve a data below provided by third party:
Data

Start: 6:00
End: 6:30
value: 1 
Start: 7:00
End: 7:30
value: 1
Start: 8:00
End: 8:30
value: 1
Start: 9:00
End: 9:30
value: 1
Start: 10:00
End: 10:30
value: 1
Start: 11:00
End: 11:30
value: 1
Start: 12:00
End: 12:30
value: 1
Start: 13:00
End: 13:30
value: 1
Start: 14:00
End: 14:30
value: 1
...
Start: 05:00
End: 05:30
value: 1

This data keeps going for a week then 30 days and 365days.

I need to transform each 30minute block in to an hour.

e.g

Start: 6:00
End: 7:00
Value: 2
Start:7:00
End: 8:00
Value:2
......

Assuming that Start, End and Value comes as one row, could someone help how above can be achieved?

Answer 1

This query is able to group by the given AggregationType and it is able to filter out incomplete groups using the second parameter checkType.

private enum AggerationType { Year = 1, Month = 2, Day = 3, Hour = 4 }

private IList<Data> RunQuery(AggerationType groupType, AggerationType checkType)
{
    // The actual query which does to trick
    var result =
        from d in testList
        group d by new {
            d.Start.Year,
            Month = (int)groupType >= (int)AggerationType.Month ? d.Start.Month : 1,
            Day = (int)groupType >= (int)AggerationType.Day ? d.Start.Day : 1,
            Hour = (int)groupType >= (int)AggerationType.Hour ? d.Start.Hour : 1
        } into g
        // The where clause checks how much data needs to be in the group
        where CheckAggregation(g.Count(), checkType)
        select new Data() { Start = g.Min(m => m.Start), End = g.Max(m => m.End), Value = g.Sum(m => m.Value) };

    return result.ToList();
}

private bool CheckAggregation(int groupCount, AggerationType checkType)
{
    int requiredCount = 1;
    switch(checkType)
    {
        // For year all data must be multiplied by 12 months
        case AggerationType.Year:
            requiredCount = requiredCount * 12; 
            goto case AggerationType.Month;
        // For months all data must be multiplied by days in month
        case AggerationType.Month:
            // I use 30 but this depends on the given month and year
            requiredCount = requiredCount * 30; 
            goto case AggerationType.Day;
        // For days all data need to be multiplied by 24 hour
        case AggerationType.Day:
            requiredCount = requiredCount * 24;
            goto case AggerationType.Hour;
        // For hours all data need to be multiplied by 2 (because slots of 30 minutes)
        case AggerationType.Hour:
            requiredCount = requiredCount * 2;
            break;

    }
    return groupCount == requiredCount;
}

Here some Test data if you want:

class Data
{
    public DateTime Start { get; set; }
    public DateTime End { get; set; }
    public int Value { get; set; }
}

// Just setup some test data simulary to your example
IList<Data> testList = new List<Data>();
DateTime date = DateTime.Parse("6:00"); 

// This loop fills just some data over several years, months and days
for (int year = date.Year; year > 2010; year--)
{
    for(int month = date.Month; month > 0; month--)
    {
        for (int day = date.Day; day > 0; day--)
        {
            for(int hour = date.Hour; hour > 0; hour--)
            {
                DateTime testDate = date.AddHours(-hour).AddDays(-day).AddMonths(-month).AddYears(-(date.Year - year));
                testList.Add(new Data() { Start = testDate, End = testDate.AddMinutes(30), Value = 1 });
                testList.Add(new Data() { Start = testDate.AddMinutes(30), End = testDate.AddHours(1), Value = 1 });
            }
        }
    }
}