Archief - MYSQL: Routeplanner

function bereken_route($StartCity){

	include ('../config/dbconfig.php');
	
	//Fill the table with initial data
	$sql = "UPDATE City SET
			 Estimate		= '2147483647',
			 Predecessor	= 'NULL',
			 Done			= '0'";
			mysql_query($sql);
	
	//Set the estimate for the city we start in to be 0.
	$sql = "UPDATE City SET Estimate = 0 WHERE CityID = '$StartCity'";
	mysql_query($sql);
	
	//Run the algorithm until we decide that we are finished
	while(1==1){
	
		//Reset the variable, so we can detect getting no records in the next step.
		$FromCity = '';
		
		//Select the CityID and current estimate for a city not done, with the lowest estimate.
		$query = "SELECT CityID, Estimate FROM City WHERE Done = 0 AND Estimate < 2147483647 ORDER BY Estimate LIMIT 1";	
		$result = mysql_db_query($dbname2, $query);
		$aanwezig = mysql_num_rows($result);
		
		if ($aanwezig != 0){
		
			while($r = mysql_fetch_array($result)){
				$FromCity 			= $r['CityID'];
				$CurrentEstimate 	= $r['Estimate'];
		
				//We are now done with this city.	
				$sql = "UPDATE City SET Done = 1 WHERE CityID = $FromCity";
				mysql_query($sql);
				
				//Update the estimates to all neighbour cities of this one (all the cities
				//there are roads to from this city). Only update the estimate if the new
				//proposal (to go via the current city) is better (lower).
				$sql = "UPDATE City INNER JOIN Road ON City.CityID = Road.ToCity 
						SET City.Estimate = $CurrentEstimate + Road.Distance, City.Predecessor = $FromCity 
						WHERE Road.FromCity = $FromCity AND ($CurrentEstimate + Road.Distance) < City.Estimate";
				
				mysql_query($sql); 
								
			}
		} else {
			break;	
		}
	}
}

function fromInPath($path, $from, $nextHop)
{
	if($path['from'] == $from && $path['from'] != $nextHop)
	{
		return 0;
	}
	return 1;
}
////////////////////////////////////////BEREKENEN ROUTE & OPSLAAN IN DB
function berekenRoute($startCity)
{

	//beginnen bij startlocatie
	$destinations[$row['CityID']] = array(
		'cost' => 0, // destination unreachable waarde
		'nextHop' => 0
	);	
	
	// alle paden ophalen
	$paths = array();
	$query = "SELECT Id, FromCity, ToCity, Distance FROM road";	
	$result = mysql_query($query);
	
	while ($row = mysql_fetch_assoc($result))
	{
		$path = array(
			'from' => $result['FromCity'],
			'to' => $result['ToCity'],
			'distance' => $result['Distance']
		);
		$paths[] = $path;
		$path = array(
			'from' => $result['ToCity'],
			'to' => $result['FromCity'],
			'distance' => $result['Distance']
		);
		$paths[] = $path;
	}
	
	// mogelijke paden berekenen naar alle volgende hops
	$nextPaths = array();
	foreach($destinations as $destination => $properties)
	{
		$nextPaths[] = array_uintersect($paths, $destination, $properties['nextHop'], "fromInPath");
	}
	
	//enkel goedkoopste paden houden
	/* verwijder paden uit nextPaths die duurder zijn dan andere paden naar dezelfde hop */

}