CODEWITHSUNDEEP
c#listdatedatetime
vkoukou
vkoukou

Reputation: 142

Group dates by week during multiple years

I have a list of DateTime values and I want to split the whole list into sublists for each week.

The dates might span across multiple years(the user selects the start and end date), so a solution that splits them up per calendar week number would end up in conflicts.

Is there a way to traverse the list and then store each week's DateTime values in a new 2d list?

The values available are from Monday to Friday and first and last week might have fewer values.

The only relevant question I found is How to group dates by weeks but it is not suitable for my case.

Upvotes: 5

Views: 1244

Answers (1)

Tim Schmelter
Tim Schmelter

Reputation: 460068

You can use this method to get the week-number of a given DateTime. Then you can use Enumerable.GroupBy with an anonymous type containing the year and the weeknum:

var yearWeekGroups = allDates.GroupBy(d => new { d.Year, WeekNum = GetIso8601WeekOfYear(d) });

If you want a List<List<DateTime>> where each sub-list contains the dates of a week:

List<List<DateTime>> allWeeks = yearWeekGroups.Select(g => g.ToList()).ToList();

If your country doesn't use ISO 8601 you can use Calendar.GetWeekOfYear:

var cc = CultureInfo.CurrentCulture;
var yearWeekGroups = allDates.GroupBy(d => new 
{ 
    d.Year, 
    WeekNum = currentCulture.Calendar.GetWeekOfYear(d, cc.DateTimeFormat.CalendarWeekRule, cc.DateTimeFormat.FirstDayOfWeek) 
});

Upvotes: 5

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