Is there an optimized way of getting business weeks between two dates?

Question

Just wondering if there is a more optimized and/or neater way (using LINQ for example) of writing what I have below to get a list of business week date ranges between two dates?

This is what I have currently ..

// Some storage
public class Bucket
{
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
}

// Other code removed for brevity ...

DateTime start = new DateTime(2015, 7, 1);
DateTime end = new DateTime(2015, 9, 1);

DayOfWeek firstDayOfWeek = DayOfWeek.Monday;
DayOfWeek lastDayOfWeek = DayOfWeek.Friday;

var buckets = new List<Bucket>();
var currentDate = start;
DateTime startOfBucket = currentDate;
DateTime endOfBucket = currentDate;
while (currentDate <= end)
{
    var currentDayOfWeek = currentDate.DayOfWeek;

    // Skip days outside the business week
    if (currentDayOfWeek >= firstDayOfWeek && currentDayOfWeek <= lastDayOfWeek)
    {
        if (currentDayOfWeek == firstDayOfWeek)
        {
            // Start a new bucket
            startOfBucket = currentDate;
        }

        if ((currentDayOfWeek == lastDayOfWeek) || (currentDate == end))
        {
            // End of bucket
            endOfBucket = currentDate;

            // Create bucket
            buckets.Add(new Bucket() 
            { 
                StartDate = startOfBucket, 
                EndDate = endOfBucket 
            });

        }
    }

    currentDate = currentDate.AddDays(1);
}

And this will give me the following date ranges ...

Start: 01/Jul/2015 End: 03/Jul/2015
Start: 06/Jul/2015 End: 10/Jul/2015
Start: 13/Jul/2015 End: 17/Jul/2015
Start: 20/Jul/2015 End: 24/Jul/2015
Start: 27/Jul/2015 End: 31/Jul/2015
Start: 03/Aug/2015 End: 07/Aug/2015
Start: 10/Aug/2015 End: 14/Aug/2015
Start: 17/Aug/2015 End: 21/Aug/2015
Start: 24/Aug/2015 End: 28/Aug/2015
Start: 31/Aug/2015 End: 01/Sep/2015

N.B. The first and last weeks are purposefully not full weeks (they abide to the date range given).

Edit The solution provided here gives the number of days between the two dates but I am interested in getting the collection of date ranges.

Also, I don't need to account for any holidays.

Thanks,

What would you want to do about public holidays? Cultures where the working week isn't always Monday to Friday? — Jon Skeet, Jul 14 '15 at 08:40
Have a look at http://stackoverflow.com/questions/1617049/calculate-the-number-of-business-days-between-two-dates — serhiyb, Jul 14 '15 at 08:41
@RoyT. his answer still iterates over each day, while accepted/upvoted answer does provide answer in O(1). — serhiyb, Jul 14 '15 at 08:45
@JonSkeet Hi Jon .. this is a basic range so not taking into account any holidays. Thanks — Gavin Sutherland, Jul 14 '15 at 08:49
@serhiyb that solution just gives the number of days. I'm interested in getting the individual date ranges. — Gavin Sutherland, Jul 14 '15 at 08:52
@GavinSutherland see the answer on that same question by José Silva ;). Thats why I said I liked that answer. — Roy T., Jul 14 '15 at 08:59

Eric · Accepted Answer · 2015-07-14T10:06:45.760

It's quite handy using linq

var startDate = new DateTime(2015, 7, 1);
var endDate = new DateTime(2015, 9, 1);
var workDates = Enumerable.Range(0, (int)(endDate - startDate).TotalDays + 1)
    .Select(i => startDate.AddDays(i))
    .Where(date => (date.DayOfWeek != DayOfWeek.Saturday && date.DayOfWeek != DayOfWeek.Sunday))
    .Select(i => i);


var display = workDates
    .GroupAdjacentBy((x, y) => x.AddDays(1) == y)
    .Select(g => string.Format("Start: {0:dd/MMM/yyyy} End: {1:dd/MMM/yyyy}", g.First(), g.Last()));

With the extension method GroupAdjacentBy<T>

public static class IEnumerableExtension
{
    public static IEnumerable<IEnumerable<T>> GroupAdjacentBy<T>(
        this IEnumerable<T> source, Func<T, T, bool> predicate)
    {
        using (var e = source.GetEnumerator())
        {
            if (e.MoveNext())
            {
                var list = new List<T> { e.Current };
                var pred = e.Current;
                while (e.MoveNext())
                {
                    if (predicate(pred, e.Current))
                    {
                        list.Add(e.Current);
                    }
                    else
                    {
                        yield return list;
                        list = new List<T> { e.Current };
                    }
                    pred = e.Current;
                }
                yield return list;
            }
        }
    }
}

Fiddle

Thanks @Eric I like this solution. I added the extension in above as it took my a minute to realize it was not a .Net extension. — Gavin Sutherland, Jul 14 '15 at 09:39

score 0 · Answer 2 · edited May 23 '17 at 12:29

This is based on Eric's accepted answer so please give him any upvote. I've just modified his solution to handle business weeks that could be 7 days long and also for one that could wrap a weekend.

var startDate = new DateTime(2015, 7, 1);
var endDate = new DateTime(2015, 9, 1);

DayOfWeek firstDayOfWeek = DayOfWeek.Monday;
DayOfWeek lastDayOfWeek = DayOfWeek.Friday;

var workDates = Enumerable.Range(0, (int)(endDate - startDate).TotalDays + 1)
            .Select(i => startDate.AddDays(i))
            .Where(date => 
                // Normal work weeks where first day of week is before last (numerically) e.g. Monday -> Friday or Sunday -> Saturday
                (firstDayOfWeek < lastDayOfWeek && date.DayOfWeek >= firstDayOfWeek && date.DayOfWeek <= lastDayOfWeek) ||
                // Cater for business weeks whose start and end dates wrap over the weekend e.g. Thursday -> Tuesday
                (lastDayOfWeek < firstDayOfWeek && (date.DayOfWeek >= firstDayOfWeek || date.DayOfWeek <= lastDayOfWeek)))
            .Select(i => i);

var display = workDates
            .GroupAdjacentBy((x, y) => x.AddDays(1) == y && !(x.DayOfWeek == lastDayOfWeek && y.DayOfWeek == firstDayOfWeek))
            .Select(g => string.Format("Start: {0:dd/MMM/yyyy} End: {1:dd/MMM/yyyy}", g.First(), g.Last()));

Is there an optimized way of getting business weeks between two dates?

2 Answers2