Btukfyl

So i have a list of locations. I need to split the list if the distance between each location is greater than say 30.

I can loop through the list and get the distance between each location, i am just not sure what the best approach is to split the list, i have read answers that break the list into chunks with a set size, but in my case the size could be variable depending on the distance between locations.

This could be really simple and i just cant see it. What i have so far is below, the code is pretty straightforward in comparing the two items, its purely splitting the list i am stuck at. Currently my code would not include all the items from the original list, it would exclude the items before the first GetRange.

var unkownSegments = grouped.Where(x => x.ActivityType == null);



foreach (var group in unkownSegments)

{

   var tempLists = new List<List<LocationResult>>();

   for (int i = 0; i < group.Items.Count - 1; i++)

   {

      var point1 = group.Items[i];

      var point2 = group.Items[i + 1];



      var sCoord = new GeoCoordinate(point1.Lat, point1.Long);

      var eCoord = new GeoCoordinate(point2.Lat, point2.Long);



      var distance = sCoord.GetDistanceTo(eCoord);



      if(distance > 30)

      {

         var tempList = group.Items.GetRange(i, group.Items.Count - i);

         tempLists.Add(tempList);

      }

   }

}

Thank you for any help or suggestions.

To create a range (using GetRange() method), you need to know where it begins and where it ends. If distance between Item[i] and Item[i+1] is greater then 30, you know the end, because that end is at index i. But you don't know the beginning (of course, you know it for the first range - it's 0), because beginning depends on the end of previous range. So you need to introduce new variable (it's called rangeStart in my example bellow), that will contain such information. It starts with value 0 (that's where first range always begins) and then update it's value whenever you add new range (next range will always start at index i+1).

After the for loop finishes, some points will remain. So need to add them points as the last range. Whole method can then look like this:

var unkownSegments = grouped.Where(x => x.ActivityType == null);



foreach (var group in unkownSegments)

{

   var tempLists = new List<List<LocationResult>>();



   //This variable keeps track of the beginning of the next range

   var rangeStart = 0;



   for (int i = 0; i < group.Items.Count - 1; i++)

   {

      var point1 = group.Items[i];

      var point2 = group.Items[i + 1];



      var sCoord = new GeoCoordinate(point1.Lat, point1.Long);

      var eCoord = new GeoCoordinate(point2.Lat, point2.Long);



      var distance = sCoord.GetDistanceTo(eCoord);



      if(distance > 30)

      {

         var tempList = group.Items.GetRange(rangeStart, i - rangeStart + 1);

         tempLists.Add(tempList);

         rangeStart = i + 1;//Next range will begin on the following item

      }

   }



   if (group.Items.Count - rangeStart > 0)

   {

      //Add all remainging (not added yet) points as the last range.

      var tempList = group.Items.GetRange(rangeStart, group.Items.Count - rangeStart);

      tempLists.Add(tempList);

   }

}