public static void WriteFlightDataWithMedoids(IList <ConsumerFlight> consumerFlights, IList <ConsumerFlight> medoids)
{
var sb = new StringBuilder();
var fileName = "flightsWithMedoids.dat";
double totalMinDistance = 0;
double averageMinDistance;
for (int i = 0; i < consumerFlights.Count; i++)
{
ConsumerFlight minDistanceMedoid = null;
double minDistance = Double.MaxValue; //distance between current flight and its closest medoid
for (int j = 0; j < medoids.Count; j++)
{
var distance = CalculateDistance(consumerFlights[i], medoids[j]);
if (distance < minDistance)
{
minDistance = distance;
minDistanceMedoid = medoids[j];
}
}
totalMinDistance += minDistance;
sb.Append(consumerFlights[i].FlightId);
sb.Append(",");
sb.Append(consumerFlights[i].SourceAirportId.ToString());
sb.Append(",");
sb.Append(consumerFlights[i].SourceLongitude);
sb.Append(",");
sb.Append(consumerFlights[i].SourceLatitude);
sb.Append(",");
sb.Append(consumerFlights[i].DestinationAirportId.ToString());
sb.Append(",");
sb.Append(consumerFlights[i].DestinationLongitude);
sb.Append(",");
sb.Append(consumerFlights[i].DestinationLatitude);
sb.Append(",");
sb.Append(consumerFlights[i].PointToPointDistance);
sb.Append(",");
sb.Append(consumerFlights[i].Price);
sb.Append(",");
sb.Append(minDistanceMedoid.FlightId);
sb.Append("\n");
}
averageMinDistance = totalMinDistance / consumerFlights.Count;
if (averageMinDistance < sampleAvgMinDistance)
{
sampleAvgMinDistance = averageMinDistance;
chosenSampleSb = sb;
chosenSampleNum = sampleNum;
}
sampleNum++;
Console.WriteLine("the avg distance for sample " + sampleNum + " is " + averageMinDistance);
}
public override bool Equals(Object obj)
{
if (obj == null || GetType() != obj.GetType())
{
return(false);
}
ConsumerFlight consumerFLight = (ConsumerFlight)obj;
return(FlightId == consumerFLight.FlightId);
}
public static double CalculateTotalSwapCost(ConsumerFlight medoid, ConsumerFlight potentialMedoid, IList <ConsumerFlight> consumerFlights, IList <ConsumerFlight> medoids)
{
double totalCost = 0;
foreach (ConsumerFlight flight in consumerFlights)
{
if (!medoids.Contains(flight) && !flight.Equals(potentialMedoid))
{
var cost = CalculateNonMedoidSwapCost(flight, medoid, potentialMedoid, consumerFlights, medoids);
totalCost += cost;
}
}
return(totalCost);
}
public static double CalculateNonMedoidSwapCost(ConsumerFlight targetNonMedoid, ConsumerFlight medoid, ConsumerFlight potentialMedoid, IList <ConsumerFlight> consumerFlights, IList <ConsumerFlight> medoids)
{
double closestDistance = Double.MaxValue;
double secondClosestDistance = Double.MaxValue;
double switchedDistance = CalculateDistance(targetNonMedoid, potentialMedoid);
double cost;
ConsumerFlight closestMedoid = null;
//finding the medoid that targetNonMedoid belongs to
foreach (var m in medoids)
{
var distance = CalculateDistance(targetNonMedoid, m);
if (distance < closestDistance)
{
closestDistance = distance;
closestMedoid = m;
}
}
if (closestMedoid.Equals(medoid))
{
//find second closest distance
foreach (var m in medoids)
{
if (!m.Equals(medoid))
{
var distance = CalculateDistance(targetNonMedoid, m);
if (distance < secondClosestDistance)
{
secondClosestDistance = distance;
}
}
}
cost = switchedDistance < secondClosestDistance
? switchedDistance - closestDistance
: secondClosestDistance - closestDistance;
}
else
{
cost = switchedDistance < closestDistance ? switchedDistance - closestDistance : 0;
}
return(cost);
}
public static IList <ConsumerFlight> RunPAM(IList <ConsumerFlight> consumerFlights, IList <ConsumerFlight> medoids)
{
var newMedoids = new List <ConsumerFlight>(medoids);
var changed = true;
while (changed)
{
changed = false;
for (int i = 0; i < medoids.Count; i++)
{
double minTotalCost = Double.MaxValue;
ConsumerFlight lowestCostNonMedoid = null;
for (int j = 0; j < consumerFlights.Count; j++)
{
if (!medoids[i].Equals(consumerFlights[j]))
{
//Console.WriteLine("comparing medoid " + medoids[i].FlightId + " with non-medoid " + consumerFlights[j].FlightId);
var currTotalCost = CalculateTotalSwapCost(medoids[i], consumerFlights[j], consumerFlights, medoids);
if (currTotalCost < minTotalCost)
{
minTotalCost = currTotalCost;
lowestCostNonMedoid = consumerFlights[j];
//Console.WriteLine("the total cost of switching " + medoids[i].FlightId + " and " + consumerFlights[j].FlightId + " is " + currTotalCost);
}
}
}
if (minTotalCost < 0 && lowestCostNonMedoid != null)
{
//Console.WriteLine("replacing medoid " + medoids[i].FlightId + " with " + lowestCostNonMedoid.FlightId + " and min cost of " + minTotalCost + "\n");
medoids[i] = lowestCostNonMedoid;
changed = true;
}
}
}
return(newMedoids);
}
public static IList <ConsumerFlight> LoadFlights(string fileName)
{
var consumerFlights = new List <ConsumerFlight>();
int errorCount = 0;
using (var flightDataStream = File.OpenText(fileName))
{
string line;
while ((line = flightDataStream.ReadLine()) != null)
{
var dataArray = Regex.Split(line, ",");
if (dataArray.Length != 9)
{
errorCount++;
}
else
{
var currentFlight = new ConsumerFlight()
{
FlightId = Int32.Parse(dataArray[0]),
SourceAirportId = Int32.Parse(dataArray[1]),
SourceLongitude = Double.Parse(dataArray[2]),
SourceLatitude = Double.Parse(dataArray[3]),
DestinationAirportId = Int32.Parse(dataArray[4]),
DestinationLongitude = Double.Parse(dataArray[5]),
DestinationLatitude = Double.Parse(dataArray[6]),
PointToPointDistance = Double.Parse(dataArray[7]),
Price = Double.Parse(dataArray[8])
};
consumerFlights.Add(currentFlight);
}
}
}
Console.WriteLine("Error Count loading flights: " + errorCount);
return(consumerFlights);
}
public static double CalculateDistance(ConsumerFlight flight1, ConsumerFlight flight2)
{
return(Math.Sqrt(Math.Pow(Math.Abs(flight1.Price - flight2.Price), 2) + Math.Pow(Math.Abs(flight1.PointToPointDistance - flight2.PointToPointDistance), 2)));
}
