Question

I have a class:

public class ShipmentInformation
{
    public string OuterNo { get; set; }
    public long Start { get; set; }
    public long End { get; set; }

}

I have a List<ShipmentInformation> variable called Results.

I then do:

List<ShipmentInformation> FinalResults = new List<ShipmentInformation>();
var OuterNumbers = Results.GroupBy(x => x.OuterNo);
foreach(var item in OuterNumbers)
{
   var orderedData = item.OrderBy(x => x.Start);

   ShipmentInformation shipment = new ShipmentInformation();
   shipment.OuterNo = item.Key;
   shipment.Start = orderedData.First().Start;
   shipment.End = orderedData.Last().End;

   FinalResults.Add(shipment);
}

The issue I have now is that within each grouped item I have various ShipmentInformation but the Start number may not be sequential by x. x can be 300 or 200 based on a incoming parameter. To illustrate I could have

1. Start = 1, End = 300
2. Start = 301, End = 600
3. Start = 601, End = 900
4. Start = 1201, End = 1500
5. Start = 1501, End = 1800

Because I have this jump I cannot use the above loop to create an instance of ShipmentInformation and take the first and last item in orderedData to use their data to populate that instance.

I would like some way of identifying a jump by 300 or 200 and creating an instance of ShipmentInformation to add to FinalResults where the data is sequnetial.

Using the above example I would have 2 instances of ShipmentInformation with a Start of 1 and an End of 900 and another with a Start of 1201 and End of 1800

Answer 1

Try the following:

private static IEnumerable<ShipmentInformation> Compress(IEnumerable<ShipmentInformation> shipments) 
{
  var orderedData = shipments.OrderBy(s => s.OuterNo).ThenBy(s => s.Start);
  using (var enumerator = orderedData.GetEnumerator())
  {
    ShipmentInformation compressed = null;
    while (enumerator.MoveNext())
    {
      var current = enumerator.Current;
      if (compressed == null) 
      {
        compressed = current;
        continue;
      }
      if (compressed.OuterNo != current.OuterNo || compressed.End < current.Start - 1)
      {
        yield return compressed;
        compressed = current;
        continue;
      }
      compressed.End = current.End;
    }

    if (compressed != null)
    {
      yield return compressed;
    }
  }
}

Useable like so:

var finalResults = Results.SelectMany(Compress).ToList();