Travelling Salesman Problem

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// Check for Self Intersection
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def pgnInt (pts:var[]..[],pnt:var)
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{
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	//Edges with existing points
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	pg01 = Polygon.ByPoints(pts).Explode();
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	in01 = 1..List.Count(pg01);
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	//Distance to New point
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	ds01 = pnt.DistanceTo(pg01);
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	//Index of closest edge to new point
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	in02 = List.SortByKey(in01,ds01)["sortedList"];
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	//Shift indices of points list
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	pt01 = List.ShiftIndices(pts,List.FirstItem(-in02));
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​
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​
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	return [Imperative]
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	{
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		bl01 = true;
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		n = 0;
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		pt11 = [];
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​
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		while (bl01)
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		{
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			// Shift insertion index
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			pt10 = List.ShiftIndices(pt01,n);
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			//Add new point to top of list
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			pt11 = List.AddItemToFront(pnt,pt10);
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			pg11 = Polygon.ByPoints(pt11);
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			//Check Self Intersection
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			it11 = pg11.SelfIntersections();
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			n = n + 1;
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			bl01 = List.Count(it11) != 0;
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		}
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		return pt11;
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	}
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};
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​
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// Add Closest Neighbour
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def clsNgh (pnt:var[]..[])
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{
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	occ = pnt[0];
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	avl = pnt[1];
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	pg01 = Polygon.ByPoints(occ);
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	ds01 = pg01.DistanceTo(avl);
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	pt01 = List.SortByKey(avl,ds01)["sortedList"];
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	pt02 = List.FirstItem(pt01);
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	pt03 = List.RestOfItems(pt01);
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	pt04 = pgnInt (occ,pt02);
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	return [pt04,pt03];
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};
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​
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// Repeat until all points are included
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def tsp (pt01:var[]..[])
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{
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	ds01 = List.FirstItem(pt01).DistanceTo(pt01);
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	pt02 = List.SortByKey(pt01,ds01)["sortedList"];
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	pt11 = [List.TakeItems(pt02,3),List.DropItems(pt02,3)];
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	return [Imperative]
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	{
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		a = [];
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		c = List.Count(pt11[1]);
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		while (c > 0)
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		{
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			a = clsNgh (pt11);
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			pt11 = a;
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			c = c - 1;
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		}
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		return a[0];
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};
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};
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​
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​
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// Implementation on lists of Random points
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n = [25,50,75,100];
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​
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pt01 = Point.ByCoordinates
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(Math.RandomList(n)*8000,Math.RandomList(n)*6000);
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​
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pt02 =tsp(pt01<1>);
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[pt02[0],GeometryColor.ByGeometryColor
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(Polygon.ByPoints(pt02[0]),Color.ByARGB(255,255,0,0))];
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[pt02[1],GeometryColor.ByGeometryColor
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(Polygon.ByPoints(pt02[1]),Color.ByARGB(255,0,255,0))];
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[pt02[2],GeometryColor.ByGeometryColor
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(Polygon.ByPoints(pt02[2]),Color.ByARGB(255,0,0,255))];
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[pt02[3],GeometryColor.ByGeometryColor
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(Polygon.ByPoints(pt02[3]),Color.ByARGB(255,255,0,250))];
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