Sampling a list with linq

I need a helper method for adding axis labels to a chart. I don't want to add a label at every point along the axis that has values in the chart because that would get too busy. So I need to extract samples at regular intervals. So far I've come up with the following method which meets the requirements but I think there must be a neater way of accomplishing this with Linq. Can anyone think of how this could be made more concise (n represents the total number of samples I want back)?

public static List<T> Sample<T>(this List<T> list, int n)
{
  var samples = new List<T>();
  var divisor = list.Count/n;
  for (var i = 0; i < list.Count; i++)
    if (samples.Count 开发者_如何学JAVA== i/divisor)
      samples.Add(list[i]);
  return samples;
}

Hm, what about:

return Enumerable.Range(0,n).Select(i=>list[(i*list.Count)/(n-1)]);

Not that it really matters, but this gives you a slightly better complexity (O(n) instead of O(list.Count)

If I understand correctly:

int divisor = list.Count / n;
return list.Where((val, index) => index % divisor == 0).ToList();

    public static List<T> Sample<T>(this List<T> list, int n)
    {
        Int32 count = list.Count;
        Int32 interval = count / n;

        return list.Where((item, index) => index % interval == 0).ToList();
    }

Try

list.Where((o, index) => index % divisor == 0)

This solution avoids using division in the iteration, which should perform faster.

public static List<T> Sample<T>(this List<T> list, int n)
{
    return list.Sample(list.Count / n).ToList();
}

public static IEnumerable<T> Sample<T>(this IEnumerable<T> enumerable, int interval) {
    var index = 0;
    foreach (var item in enumerable) {
        if (index == 0) {
            yield return item;
        }
        if (++index == interval) index = 0;
    }
}