忘れやすい拡張メソッドまとめ

EnumerableExtensions.cs

public static class EnumerableExtensions
{
    // https://stackoverflow.com/questions/3210824/divide-array-into-an-array-of-subsequence-array/29462069
    public static IEnumerable<IEnumerable<TSource>> Batch<TSource>(this IEnumerable<TSource> source, int size)
    {
        if (source == null)
        {
            throw new ArgumentNullException(nameof(source));
        }

        if (size < 1)
        {
            throw new ArgumentOutOfRangeException(nameof(size));
        }

        using (var enumerator = source.GetEnumerator())
        {
            while (enumerator.MoveNext())
            {
                var batch = new List<TSource>(size)
                {
                    enumerator.Current
                };
                    
                for (int i = 1; i < size && enumerator.MoveNext(); i++)
                {
                    batch.Add(enumerator.Current);
                }

                yield return batch;
            }
        }
    }
}