Inactive Interval of a day in TimeSpan

Question

I have a c# class named Slot which only accept values from 0:00:00 to 1.00:00:00 for all its TimeSpan properties.

public class Slot
{
    public TimeSpan StartTime { get; set; }

    public TimeSpan EndTime { get; set; }

}

I have these values as my active Intervals which don't overlap each other:

var activeIntervals= new List<Slot>
{
    new Slot
    {
        StartTime = new TimeSpan(10,0,0),
        EndTime = new TimeSpan(12,0,0),
    },
    new Slot
    {
        StartTime = new TimeSpan(12,0,0),
        EndTime = new TimeSpan(13,0,0),
    },
    new Slot
    {
        StartTime = new TimeSpan(16,0,0),
        EndTime = new TimeSpan(22,0,0),
    }
};

Is there any logic to get the other intervals of the day as inactiveIntervals?

In this case i want this result: 0:00:00 to 10:00:00, 13:00:00 to 16:00:00 and 22:00:00 to 1.00:00:00

Is it just your example that doesn't happen to overlap or does your system not allow for overlap at all? — Lasse V. Karlsen, Nov 05 '18 at 10:12
@dumetrulo that is my requirement and i can't help you with that. — Farshan, Nov 05 '18 at 10:12
@dumetrulo Probably because there is no "time" data type in .NET — Lasse V. Karlsen, Nov 05 '18 at 10:12
You will need to find all the "holes" between the slots, should be rather easy with a loop, and you need to consider if you want to include midnight->first slot and last slot->midnight as well. — Lasse V. Karlsen, Nov 05 '18 at 10:20
@LasseVågsætherKarlsen You mean looping through every single minutes between 0 and 24? — Farshan, Nov 05 '18 at 10:27
Just a note, as not answering the question. Have you considered the longest day of the year (28 Oct 2018 in UK this year), it is 25 hours long. — ctrl-alt-delor, Nov 05 '18 at 10:33
No, sort them, then the first interval is from midnight to the first slot, then if the first slot and the next slot has a gap between them, that's also such an interval, and then go from there. — Lasse V. Karlsen, Nov 05 '18 at 11:53
@ctrl-alt-delor you are talking about the dst, right? It won't be affecting my system because i'm not dealing with DateTime. But i appreciate your valuable note. — Farshan, Nov 06 '18 at 09:47

score 2 · Accepted Answer · answered Nov 05 '18 at 10:27

Try below logic. It will work for you.

You can test it here

var activeIntervals = new List<Slot>
{
    new Slot
    {
        StartTime = new TimeSpan(10,0,0),
        EndTime = new TimeSpan(12,0,0),
    },
    new Slot
    {
        StartTime = new TimeSpan(12,0,0),
        EndTime = new TimeSpan(13,0,0),
    },
    new Slot
    {
        StartTime = new TimeSpan(16,0,0),
        EndTime = new TimeSpan(22,0,0),
    }
};


activeIntervals = activeIntervals.OrderBy(x => x.StartTime).ToList();

var inActiveIntervals = new List<Slot>();
TimeSpan start =  new TimeSpan(0,0,0);
TimeSpan end =  new TimeSpan(24,0,0);

for (int i = 0; i < activeIntervals.Count(); i++)
{
    if (start < activeIntervals[i].StartTime) 
    {
        inActiveIntervals.Add(new Slot { StartTime = start, EndTime = activeIntervals[i].StartTime });
    }
    start = activeIntervals[i].EndTime;
}            
if (start < end) 
{
    inActiveIntervals.Add(new Slot { StartTime = start, EndTime = end });
    start = end;
}
for (int i = 0; i < inActiveIntervals.Count(); i++)
{
     Console.WriteLine(inActiveIntervals[i].StartTime.ToString() + " - " + inActiveIntervals[i].EndTime.ToString());
}

This is what i was looking for. Thanks mate – Farshan Nov 05 '18 at 10:39 — Farshan, Nov 05 '18 at 10:39

FCin · Answer 2 · 2018-11-05T10:34:04.117

1

One idea with linq:

var inactiveIntervals = activeIntervals
    .Zip(activeIntervals.Skip(1), (first, second) => {
        if (second.StartTime - first.EndTime != TimeSpan.Zero) // Get rid of regions that don't have 'gap', e.g. 12:00:00 to 12:00:00
            return new Slot { StartTime = first.EndTime, EndTime = second.StartTime };
        return null;
    }).Where(a => a != null).ToList(); // Filter out nulls

// Insert range from start to first date
inactiveIntervals.Insert(0, new Slot { StartTime = TimeSpan.Zero, EndTime = activeIntervals[0].StartTime });
// Insert range from last date to end
inactiveIntervals.Add(new Slot { StartTime = activeIntervals.Last().EndTime, EndTime = new TimeSpan(1, 0, 0, 0) });

This uses a trick with .Zip where you take a list and then zip it with the same list moved by 1. Then you can compare EndTime from one element with StartTime from next element.

Filtering regions without gaps is kind of ugly. You have to check edge cases.

edited Nov 05 '18 at 10:34

answered Nov 05 '18 at 10:28

FCin

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This seems like too costly. – Farshan Nov 05 '18 at 10:34
@Farshan What do you mean? – FCin Nov 05 '18 at 10:34
Using linq is very expensive than loop [link](https://stackoverflow.com/questions/14893924/for-vs-linq-performance-vs-future) – Farshan Nov 05 '18 at 10:36
@Farshan Don't optimize something that isn't a bottleneck. How do you know if this is going to slow down your application considerably? Profile it first. – FCin Nov 05 '18 at 10:39
because optimisation is my prior concern. But thanks for immediate help – Farshan Nov 05 '18 at 10:41

Alexander · Answer 3 · 2018-11-05T10:44:47.023

You need to create new instance of List<Slot> and then add intervals of day that does not exist in activeIntervals list using iteration of the list elements.

public static class SlotExtensions
{
    public static List<Slot> GetInactive(this List<Slot> slots)
    {
        Slot day = new Slot
        {
            StartTime = new TimeSpan(0,0,0),
            EndTime = new TimeSpan(24,0,0)
        }
        List<Slot> inactive = new List<Slot>();
        Slot tmp;
        foreach(Slot slot in slots)
        {
            if(day.StartTime < slot.StartTime)
            {
                tmp = new Slot
                {
                    StartTime = day.StartTime;
                    EndTime = slot.StartTime;
                };
                inactive.Add(tmp);
            };
            day.StartTime = slot.EndTime;
        }
        if(day.StartTime < day.EndTime)
        {
            inactive.Add(day);
        }
        return inactive;
    }
}

The extension method uses day, that is an instanse of Slot class and fits full day. Then we add difference between starts of the day and iterated slot to a new list and then shift start of the day to end of iterated slot. When loop is over the metod adds remainig interval to the list.

Inactive Interval of a day in TimeSpan

3 Answers3