Split array or list into segments using LINQ

Question

This question is slightly different from here

I have an array of numbers where I want to produce a list of segments. The end of the segment is included as the beginning element of the next segment. I want each segment to have 3 (in this example) points each. Here's an illustration:

var origArray = new[] {1,2,3,4,5,6};

I want the result to be:

{ {1,2,3}, {3,4,5}, {5,6} }

A traditional for-loop could accomplish this, but just wondering if somebody did this in a LINQy way.

I'm not the downvoter, but you could very easily modify the code in the accepted answer of the question you linked to in order to do what you want to do. — CoderDennis, Jul 24 '16 at 02:25

score 3 · Answer 1 · edited Apr 24 '21 at 14:04

Try adding the Microsoft's Reactive Framework Team's Interactive Extensions - just NuGet "Ix-Main".

Then you can do this:

var origArray = new[] {1,2,3,4,5,6};
var result = origArray.Buffer(3, 2);

The two parameters are "how many to group", 3, and "how many to skip", 2.

The result is as you expect: { {1,2,3}, {3,4,5}, {5,6} }.

This is their implementation from https://github.com/dotnet/reactive/blob/main/Ix.NET/Source/System.Interactive/System/Linq/Operators/Buffer.cs:

    private static IEnumerable<IList<TSource>> Buffer_<TSource>(this IEnumerable<TSource> source, int count, int skip)
    {
        var buffers = new Queue<IList<TSource>>();

        var i = 0;
        foreach (var item in source)
        {
            if (i%skip == 0)
                buffers.Enqueue(new List<TSource>(count));

            foreach (var buffer in buffers)
                buffer.Add(item);

            if (buffers.Count > 0 && buffers.Peek()
                                            .Count == count)
                yield return buffers.Dequeue();

            i++;
        }

        while (buffers.Count > 0)
            yield return buffers.Dequeue();
    }

score 0 · Answer 2 · answered Jul 24 '16 at 02:56

Two possible ways to do this using Linq.

var segmentedArray1 = origArray
    .Select((item, index) => new { item, index })
    .GroupBy(x => x.index/3)
    .Select(@group => @group.Select(x=>x.item));

var segmentedArray2 = Enumerable.Range(0, origArray.Count())
    .GroupBy(x => x/3)
    .Select(@group => @group.Select(index => origArray[index]));

Here's a dotnetfiddle

Split array or list into segments using LINQ

2 Answers2