How to group items by index? C# LINQ

Question

Suppose I have

var input = new int[] { 0, 1, 2, 3, 4, 5 };

How do I get them grouped into pairs?

var output = new int[][] {         


        

Answer 1

Using ToLookup method:

input
    .Select((number, index) => new { index , number})
    .ToLookup(_ => _.index / 2, _ => _.number)
    .Select(_ => _.ToArray())
    .ToArray();

Using Zip method:

input
    .Zip(input.Skip(1), (_, __) => new[] {_, __})
    .Where((_, index) => index % 2 == 0)
    .ToArray();