I'm looking for a way to compute the range of a give set of number for example.
if I had H555,H567,H589,H590,H591,H592,H593,H594,H595,H596,H597
I would like output of H555,H567,H589-H597.
I have looked through relevant questions and can not find anything like what I'm looking for.
Thanks
Well, I'd do something like this:
public sealed class Range { public int Low { get; private set; } public int High { get; private set; } public Range(int low, int high) { this.Low = low; this.High = high; } } Then (completely untested, may not even compile, but hopefully you'll get the drift):
public static IEnumerable<Range> FindRanges(IEnumerable<int> values) { using (IEnumerator<int> iterator = values.GetEnumerator()) { if (!iterator.MoveNext()) { yield break; } int low = iterator.Current; int high = low; while (iterator.MoveNext()) { int next = iterator.Current; if (next > high + 1) { // Previous range (or possibly single value) has finished yield return new Range(low, high); low = next; } high = next; } // Yield trailing range yield return new Range(low, high); } } I don't think this is particularly easy to do using straight LINQ, to be honest.
EDIT: To adapt this now that everything starts with H, just use:
var numbers = strings.Select(x => int.Parse(x.Substring(1)); var ranges = FindRanges(numbers); var rangeStrings = ranges.Select(r => r.High == r.Low ? "H" + r.Low : "H" + r.Low + "-" + r.High); var result = string.Join(",", rangeStrings); 
I think that Linq is really overhead here but if you want it here you are:
int[] arr = { 555, 567, 589, 590, 591, 592, 593, 594, 595, 596, 597 }; int gr = 0; var q = arr .Skip(1) .Select((x, i) => new { x, group = (x - arr[i]) == 1 ? gr : gr++ }) .GroupBy( a => a.group) .Select( a => a.Count() == 1 ? a.First().x.ToString() : string.Format("{0}-{1}", a.First().x, a.Last().x)); foreach (var item in q) { Console.Write(item); Console.Write(", "); } 
