C# - elegant way of partitioning a list?

Question

I\'d like to partition a list into a list of lists, by specifying the number of elements in each partition.

For instance, suppose I have the list {1, 2, ... 11}, and

Answer 1

To avoid grouping, mathematics and reiteration.

The method avoids unnecessary calculations, comparisons and allocations. Parameter validation is included.

Here is a working demonstration on fiddle.

public static IEnumerable> Partition(
    this IEnumerable source,
    int size)
{
    if (size < 2)
    {
        throw new ArgumentOutOfRangeException(
            nameof(size),
            size,
            "Must be greater or equal to 2.");  
    }

    T[] partition;
    int count;

    using (var e = source.GetEnumerator())
    {
        if (e.MoveNext())
        {
            partition = new T[size];
            partition[0] = e.Current;
            count = 1;
        }
        else
        {
            yield break;    
        }

        while(e.MoveNext())
        {
            partition[count] = e.Current;
            count++;

            if (count == size)
            {
                yield return partition;
                count = 0;
                partition = new T[size];
            }
        }
    }

    if (count > 0)
    {
        Array.Resize(ref partition, count);
        yield return partition;
    }
}