Query_NN.sml

#********************************************************************
#The following code prints out a list of the nearest
#neighbor polygons after querying the user for a vector object
#and a polygon number:

# QRY_NN.SML
# Given a single polygon of a vector object,
# print out the nearest neighbor polygons.
# AUTHOR: Paul Pope, Environmental Monitoring Program, UW-Madison
# LAST MODIFIED: April 12, 1997

clear();

vector V;

# Prompt the user to enter the vector object
GetInputVector(V);

# Prompt the user to enter a polygon number of the vector object
numeric number_of_polygons = NumVectorPolys(V);
string prompt$ = "Enter the polygon ID number";
numeric polygon_ID_number = PopupNum(prompt$, 1, 1, number_of_polygons);

array numeric line_list[1];
array numeric nearest_neighbor_list[1];

numeric number_of_lines, number_of_neighbors;
number_of_lines = GetVectorPolyLineList(V,line_list, polygon_ID_number);
print("Number of Lines = ", number_of_lines);

number_of_neighbors = 0;

# Loop over the number of lines that make up the
# polygon and determine the nearest neighbor polygons
numeric j, k;
numeric leftpoly, rightpoly, outside_polygon, flag;
for j = 1 to number_of_lines step 1
{
	print("Line Number = ", line_list[j]);

	leftpoly = V.line[line_list[j]].Internal.LeftPoly;
	rightpoly = V.line[line_list[j]].Internal.RightPoly;

	print("Left Poly = ", leftpoly, "Right Poly = ", rightpoly);

	# A nearest neighbor polygon will be either
	# the leftpoly or the rightpoly to the line being evaluated
	if (leftpoly != polygon_ID_number) then
	{
		outside_polygon = leftpoly;
	}
	if (rightpoly != polygon_ID_number) then
	{
		outside_polygon = rightpoly;
	}

	# Ensure that this nearest neighbor has not
	# already been accounted for
	flag = 0;
	for k = 1 to number_of_neighbors step 1
	{
		if (nearest_neighbor_list[k] == outside_polygon) then
		{
			flag = 1;
		}
	}

	# If this nearest neighbor has not been
	# accounted for already, then add it to
	# the list of nearest neighbors
	if (flag != 1) then
	{

		# Make a copy of the nearest neighbor list
		if (number_of_neighbors > 0) then
		{
			array numeric temp_list[number_of_neighbors];
			for k = 1 to number_of_neighbors step 1
			{
				temp_list[k] = nearest_neighbor_list[k];
			}
		}

		# Redefine the number of elements in the list
		# of nearest neighbors and add the new nearest
		# neighbor to the end of the list
		number_of_neighbors = number_of_neighbors + 1;
		array numeric nearest_neighbor_list[number_of_neighbors];
		nearest_neighbor_list[number_of_neighbors] = outside_polygon;

		# Copy all of the previously determined nearest
		# neighbors into the newly expanded list
		if (number_of_neighbors > 1) then
		{
			for k = 1 to (number_of_neighbors - 1) step 1
			{
				nearest_neighbor_list[k] = temp_list[k];
			}
		}

		print("Nearest Neighbor = ", outside_polygon);

	}  # End of if-then statement

}  # End of looping over j, the number of lines

# Clear the console and print out the list
# of nearest neighbors
clear();
print("For Polygon ID number = ", polygon_ID_number,", ");
print("the number of nearest neighbors = ", number_of_neighbors);
for k = 1 to number_of_neighbors step 1
{
	print("Nearest Neighbor[", k, "] = ", nearest_neighbor_list[k]);
}

# End of SML script