Question

Possible Duplicate:
LINQ Partition List into Lists of 8 members
how do I chunk an enumerable?

I have a list of many items, and a Method that works well on shorter lists of those same items.

Can I use LINQ to pull off N elements from the big list, and pass them into the Method, N at a time? I’m sure there is an elegant way to to this without having to make an “int i=0;” variable.

Let me be clear, I know that foo.Take(10) will get me 10 items off the list. But I need to keep processing the next set of 10, then the next set of 10 and so on. The pseudo code should be something like:

var shortList = BigList.NiceMethod(10);
foreach (shorty in shortlist)
{
  Method(shorty);
}

This is probably some Group call.

Answer 1

This will give you a list of Lists where every List has at most N elements.

int N = 3;
List<int> list = new List<int>() { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

var ListOfLists = list.Select((x, inx) => new { Item = x, Group = inx / N })
                        .GroupBy(g => g.Group, g => g.Item)
                        .Select(x => x.ToList())
                        .ToList();

You can also use Morelinq’s Batch method

var ListOfLists2 = list.Batch(3).Select(x => x.ToList()).ToList();