Finding Consecutive Items in List using Linq

Question

Say I have the following array of integers:

int[] numbers = { 1, 6, 4, 10, 9, 12, 15, 17, 8, 3, 20, 21, 2, 23, 25, 27, 5, 67,33, 13, 8, 12, 41, 5 };
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Answer 1

Why don't you try this extension method?

public static IEnumerable> Consecutives(this IEnumerable numbers, int ranges, Func predicate)
{
    IEnumerable ordered = numbers.OrderBy(a => a).Where(predicate);
    decimal n = Decimal.Divide(ordered.Count(), ranges);
    decimal max = Math.Ceiling(n); // or Math.Floor(n) if you want
    return from i in Enumerable.Range(0, (int)max)
           select ordered.Skip(i * ranges).Take(ranges);
}

The only thing to improve could be the call to Count method because causes the enumeration of numbers (so the query loses its laziness).

Anyway I'm sure this could fit your linqness requirements.

EDIT: Alternatively this is the less words version (it doesn't make use of Count method):

public static IEnumerable> Consecutives(this IEnumerable numbers, int ranges, Func predicate)
{
    var ordered = numbers.OrderBy(a => a);
    return ordered.Where(predicate)
                  .Select((element, i) => ordered.Skip(i * ranges).Take(ranges))
                  .TakeWhile(Enumerable.Any);
}