CODEWITHSUNDEEP
c#linqlambda
user2112420
user2112420

Reputation: 985

C# Linq or Lambda expression Group by Week IEnumerable list with date field

I am trying to do a query to an IEnumerable<Object> to group by week, for example:

Project(Name, DateStart,ID)

I have IEnumerable<Project> and I want to do a report, grouping by week.

For exmaple:

Week 1
 Project1  8/4/2013 ID1
 Project2  9/4/2013 ID2
Week 2
 Project1  16/4/2013 ID3
 Project2  18/4/2013 ID5
Week 3
 Project1  24/4/2013 ID7
 Project2  26/4/2013 ID8

Please if someone can give me a hand I really appreciate it! I was trying to do a lambda expression but without success.

Thanks!

Upvotes: 4

Views: 12359

Answers (6)

hoss77
hoss77

Reputation: 385

In addition to Tim Schmelter's answer you can get the date of the first day in the week then group by that date.

To get the date of the first day in the week. you can use this code:

public static class DateTimeExtensions
{
    public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)
    {
        int diff = dt.DayOfWeek - startOfWeek;
        if (diff < 0)
        {
            diff += 7;
        }
        return dt.AddDays(-1 * diff).Date;
    }
}

then you can group by the first date of the week like this:

var weekGroups = projects
    .Select(p => new 
    { 
        Project = p
    })
    .GroupBy(x => x.Project.DateStart.StartOfWeek(DayOfWeek.Monday))
    .Select((g, i) => new 
    { 
        WeekGroup = g, 
        WeekNum = i + 1
    });

foreach (var projGroup in weekGroups)
{
    Console.WriteLine("Week " + projGroup.WeekNum);
    foreach(var proj in projGroup.WeekGroup)
        Console.WriteLine("{0} {1} {2}", 
            proj.Project.Name, 
            proj.Project.DateStart.ToString("d"), 
            proj.Project.ID);
}

Upvotes: 0

Juan Ayala
Juan Ayala

Reputation: 3528

You can use the GetWeekOfMonth extension posted here:

and then do something like:

        var groups = projects.GroupBy(p => p.Start.GetWeekOfMonth());

        foreach (var group in groups)
        {
            Console.WriteLine("Week {0}", group.Key);
            foreach (var project in group)
            {
                Console.WriteLine("\t{0} | {1:dd/MM/yyyy} | {2}", 
                     project.Name, project.Start, project.Id);
            }
        }

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460288

var weekGroups = projects
    .Select(p => new 
    { 
        Project = p, 
        Year = p.DateStart.Year, 
        Week =  CultureInfo.InvariantCulture.Calendar.GetWeekOfYear
                      (p.DateStart, CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday)
    })
    .GroupBy(x => new { x.Year, x.Week })
    .Select((g, i) => new 
    { 
        WeekGroup = g, 
        WeekNum = i + 1,
        Year = g.Key.Year,
        CalendarWeek = g.Key.Week
    });

foreach (var projGroup in weekGroups)
{
    Console.WriteLine("Week " + projGroup.WeekNum);
    foreach(var proj in projGroup.WeekGroup)
        Console.WriteLine("{0} {1} {2}", 
            proj.Project.Name, 
            proj.Project.DateStart.ToString("d"), 
            proj.Project.ID);
}

Upvotes: 14

Alex
Alex

Reputation: 7919

You will need to define a function that can determine which week a date is in:

int GetWeek(DateTime date) { ... }

Then the LINQ query to group is:

IEnumerable<IGrouping<int, Project>> groupedProjects = 
         myListOfProjects.GroupBy(p => GetWeek(p.DateStart));

You can iterate over the grouped projects list:

foreach (var weekGroup in groupedProjects)
{
    int week = weekGroup.Key;
    foreach (var project in weekGroup)
    {
        Console.WriteLine("Week " + week + " | Project: " + project.ID);
    }
}

Upvotes: 1

code4life
code4life

Reputation: 15794

I think just a simple projection will suffice:

// we'll just use the existing settings on the box.
DateTimeFormatInfo dfi = DateTimeFormatInfo.CurrentInfo;
var cal = dfi.Calendar;

var Projects = GetProjectsFromSomewhere(); // assuming IEnumerable<Project>

int week = 1; // this *could* be changed and projected in the Select instead.
foreach (var wg in from p in Projects
    group p by cal.GetWeekOfYear(
        p.StartDate, dfi.CalendarWeekRule, dfi.FirstDayOfWeek))
{
    Console.WriteLine("Week {0}", week);

    foreach (var p in wg)
    {
        Console.WriteLine("    {0} {1} {2}", p.Name, p.StartDate, p.ID);
    }
    week++;
}

Upvotes: 0

Sergey K
Sergey K

Reputation: 4114

I think to simplify this task you can add WeekNumber property into Project class and fill it when you are creating object of Project after you can easy group by WeekNumber property

Project(Name, DateStart,ID,WeekNumber)

Upvotes: 0

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