private static void Execute()
{
// Process data files
var airports = AirportCollection.LoadFromFile(AirportsFilePath);
var adsbEvents = LoadFromFile(AdsbEventsFilePath);
Console.WriteLine($"Loaded {airports.Count} airports and {adsbEvents.Count} events");
// Sort events by aircraft
var allAircraft = new Dictionary <string, Aircraft>();
adsbEvents.ForEach((adsbEvent) =>
{
if (allAircraft.TryGetValue(adsbEvent.Identifier, out Aircraft aircraft))
{
aircraft.AdsbEvents.Add(adsbEvent);
}
else
{
allAircraft.Add(adsbEvent.Identifier,
new Aircraft(adsbEvent.Identifier, new List <AdsbEvent>()
{
adsbEvent
}));
}
});
Console.WriteLine($"Identified {allAircraft.Count} aircraft");
// Find potential flights
var flights = new List <Flight>();
allAircraft.Select(kv => kv.Value).ToList().ForEach((aircraft) =>
{
var flight = new Flight()
{
AircraftIdentifier = aircraft.AircraftIdentifier
};
// Filter out events without coordinates
var aircraftEvents = aircraft.AdsbEvents
.Where(adsbEvent => adsbEvent.Latitude != null && adsbEvent.Longitude != null)
.OrderBy(adsbEvent => adsbEvent.Timestamp);
// Implement a sliding window by analyzing the altitude data
// This could also be implemented by analyzing the speed data, but the altitude data is
// more consistent
var events = aircraftEvents.Where(adsbEvent => adsbEvent.Altitude != null);
var step = 10;
var sampleSize = 25;
var previousTrend = Trend.Unknown;
// Check the start events for departure
var startSample = events.Take(sampleSize);
if (startSample.First().Altitude < startSample.Last().Altitude)
{
flight.DepartureTime = events.First().Timestamp;
flight.DepartureAirport = airports.GetClosestAirport(events.First().GeoCoordinate).Identifier;
}
// Check the middle events for additional flights
for (var i = 0; i < events.Count() - sampleSize; i += step)
{
var sample = events.Skip(i).Take(sampleSize);
var currentTrend = GuessTrend(sample.Select(adsbEvent => adsbEvent.Altitude.Value));
// If the aircraft's altitude trend changes from decreasing to increasing below the altitude threshold,
// assume that it's started a new flight
if (previousTrend == Trend.Decrease &&
currentTrend == Trend.Increase &&
sample.First().Altitude < MAX_ALTITUDE)
{
var airport = airports.GetClosestAirport(sample.First().GeoCoordinate);
// If there isn't an airport nearby, the airplane may have made an unexpected descent and ascent
if (airport == null)
{
continue;
}
// Check if the aircraft is flying over the airport
if (Math.Abs(airport.Elevation - sample.First().Altitude.Value) >= GROUND_TOLERANCE)
{
continue;
}
flight.ArrivalTime = sample.First().Timestamp;
flight.ArrivalAirport = airport.Identifier;
flights.Add(flight);
flight = new Flight
{
AircraftIdentifier = aircraft.AircraftIdentifier,
DepartureTime = sample.Last().Timestamp,
DepartureAirport = airports.GetClosestAirport(sample.Last().GeoCoordinate).Identifier
};
}
previousTrend = currentTrend;
}
// Check the end events for arrival
var endSample = events.TakeLast(sampleSize);
if (endSample.First().Altitude > endSample.Last().Altitude)
{
flight.ArrivalTime = events.Last().Timestamp;
flight.ArrivalAirport = airports.GetClosestAirport(events.Last().GeoCoordinate).Identifier;
}
if (flight.DepartureAirport != null || flight.ArrivalAirport != null)
{
flights.Add(flight);
}
});
Console.WriteLine($"Identified {flights.Count} potential flights");
WriteResults(flights);
}