Kijana Woodard

[Edit: See the comments to see why this post is totally unnecessary. Thanks Matt!]

I found myself in an odd situation. I had a List of objects that I needed to break into a List of Lists to make display a little more, well, sane. I did a web search and found a couple entries detailing how to break a list into fixed sized chunks.

However, my situation was such that each partition could vary in size.

I have a class that looks roughly like this:

private class Score
{
    public int ScoreTypeId { get; set; }
    public double Score { get; set; }
    public int DivisionId { get; set; }
}

Some divisions have 11 "ScoreTypes", some have 10, some have 7, etc. So I needed a way to break up my single list (the result of a db query) into chunks to give to my View code.

I came up with this:

public static class IEnumerableExtender
{
    public static IEnumerable<IEnumerable<T>> Partition<T, TResult>(
             this IEnumerable<T> list, Func<T, TResult> partition)
    {
        var elements = list.Select(partition).Distinct();
        foreach (var item in elements)
        {
            yield return list.Where(x => partition(x).Equals(item));
        }
    }
}

//usage:
var final = list.Partition(x => x.DivisionId );

I'm pretty happy with this. I played around partitioning by different elements and even a bit with partitioning by multiple elements. It kept on producing expected results.

p.s.

That MoreLinq project by Jon Skeet mentioned in the StackOverflow post looks interesting. I didn't get a chance to go through it yet.