[tsp_getcosts]

Description

This tag accepts a nested array of coordinates and generates a cost matrix, using [tsp_getdistance] to calculate the distance from each point to every other point in the list. This matrix provides the data necessary for [tsp_gettour] to calculate a "next-closest tour" to solve basic TSP problems.

Requires [tsp_getdistance], available here.

Sample Usage

// test data	
var('cities') = array(
	'Location A' = array(-82.521102,37.484227),
	'Location B' = array(-84.622564,37.059857),
	'Location C' = array(-84.622668,37.059893),
	'Location D' = array(-82.642757,38.480449),
	'Location E' = array(-84.600683,37.031884),
	'Location F' = array(-85.062656,36.982708),
	'Location G' = array(-84.623724,37.055167),
	'Location H' = array(-84.622564,37.059857),
	'Location I' = array(-84.072400,37.107600),
	'Location J' = array(-84.335426,36.841322)	
);

// cost example 	
// need an array of just the coordinate pairs	
var('points' = array);

'Raw Order
\n';

iterate($cities, local('i'));
	// just to show the original order
	loop_count + '. ' + #i->first + '
\n';

	// Flipping x/y values because my test data is backwards...
	$points->insert(array(#i->second->get(2),#i->second->get(1)));
/iterate;

var('costs') = tsp_getcosts($points);

// show the matrix
'

Cost Matrix:
\n';
'\n';

iterate($costs, local('i'));
	'';
	
	iterate(#i, local('x'));
		local('x') = decimal(#x);
		#x->setformat( -precision=6);
	
		'';
	/iterate;
	
	'\n';
/iterate;

'
' + decimal(#x) + '
\n';

Source Code

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define_tag(
	'getcosts',
	-namespace='tsp_',
	-priority='replace',
	-required='points',
	-type='array',
	-description='Generate a cost matrix for a set of points.'
);
	local('out' = array);
	
	iterate(#points, local('startSet'));
		local('tmp' = array);
	
		iterate(#points, local('costSet'));
			local('distance') = @tsp_getdistance(
				-startLat = #startSet->get(1),
				-startLong = #startSet->get(2),
				-endLat = #costSet->get(1),
				-endLong = #costSet->get(2)
			);
			
			#tmp->insert(#distance);
		/iterate;
		
		#out->insert(#tmp);
	/iterate;
	
	return(#out);
/define_tag;

Related Tags

• tsp_geocode
• tsp_getdistance
• tsp_gettour

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