c# - ASP.NET MVC Filter datetime by weeks -

i've got web api , method, returning query:

var query = results in context.questionaireresults             results.departuredate >= startdate && results.departuredate <= enddate             select new  {  week = { need method group weeks }, average = results.where(x => x.number).average() }  return query.tolist(); 

i want calculate average each 7 days (that being first week).

example:

average 1 ... day 7 (week 1) average 2 ... day 14 (week 2) 

how can that? being given interval of datetimes, filter weeks (not week of year)

try (not tested tables)

var avgresult = context.questionaireresults                .where(r => (r.departuredate >= startdate && r.departuredate <= enddate)).tolist()                .groupby( g => (decimal.round(g.departuredate.day / 7)+1))                .select( g => new                 {                    week = g.key,                    avg = g.average(n => n.number)                 });