从 stackoverflow.com 上抄来的，将 IEnumerable 中的元素进行切分的方法，无动态内存分配，地球上最快的实现：
public static class LinqExtensions
{
/// <summary>
/// 将 source 中的条目按照 partitionSize 指定的每组数量进行分组
/// http://stackoverflow.com/questions/3773403/linq-partition-list-into-lists-of-8-members
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="partitionSize"></param>
/// <returns></returns>
public static IEnumerable<IEnumerable<T>> Partition<T>(this IEnumerable<T> source, int partitionSize)
{
if (partitionSize <= )
{
throw new ArgumentOutOfRangeException(nameof(partitionSize));
} int innerListCounter = ;
int numberOfPackets = ;
foreach (var item in source)
{
innerListCounter++;
if (innerListCounter == partitionSize)
{
yield return source.Skip(numberOfPackets * partitionSize).Take(partitionSize);
innerListCounter = ;
numberOfPackets++;
}
} if (innerListCounter > )
{
yield return source.Skip(numberOfPackets * partitionSize);
}
} /// <summary>
/// 将 source 中的条目按照 numberOfChunks 参数指定的分组数进行切分
/// http://stackoverflow.com/questions/438188/split-a-collection-into-n-parts-with-linq/13744322#13744322
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="numberOfChunks"></param>
/// <returns></returns>
public static IEnumerable<IEnumerable<T>> Split<T>(this ICollection<T> source, int numberOfChunks)
{
if (numberOfChunks <= || numberOfChunks > source.Count)
{
throw new ArgumentOutOfRangeException(nameof(numberOfChunks));
} int sizePerPacket = source.Count / numberOfChunks;
int extra = source.Count % numberOfChunks; for (int i = ; i < numberOfChunks - extra; i++)
{
yield return source.Skip(i * sizePerPacket).Take(sizePerPacket);
} int alreadyReturnedCount = (numberOfChunks - extra) * sizePerPacket;
int toReturnCount = extra == ? : (source.Count - numberOfChunks) / extra + ;
for (int i = ; i < extra; i++)
{
yield return source.Skip(alreadyReturnedCount + i * toReturnCount).Take(toReturnCount);
}
} }
两个方法以不同的形式对 IEnumerable 集合中的元素进行分组，非常有用，而且没有容器操作等动态内存分配，不可能再快了。