public Link FindLink(City u, City n, Link.TransportModeEnum tmode)
{
return(links.Find(l => l.FromCity.Equals(u) &&
l.ToCity.Equals(n) ||
l.ToCity.Equals(u) &&
l.FromCity.Equals(n)));
}
public Link FindLink(City from, City to, Link.TransportModeEnum t)
{
return(links.Find(l =>
(l.FromCity.Equals(from) &&
l.ToCity.Equals(to) ||
l.FromCity.Equals(to) &&
l.ToCity.Equals(from)) && l.TransportMode == t));
}
public IEnumerable <City> FindNeighbors(City u, Link.TransportModeEnum tmode)
{
return((from l in links
where l.FromCity.Equals(u)
select l.ToCity).Union(
from l in links
where l.ToCity.Equals(u)
select l.FromCity).ToList());
}
public List <City> FindNeighbours(City
c, Link.TransportModeEnum t)
{
return((from l in links
where l.FromCity.Equals(c)
select l.ToCity).Union(
from l in links
where l.ToCity.Equals(c)
select l.FromCity).ToList());
}
/** find shortest path between source to target city
* {@link http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm}
*
* @return itinerary
*/
public Link[] FindShortestRouteBetween(string fromName, String toName,
Link.TransportModeEnum tmode)
{
City source = cityRepository.FindByName(fromName);
City target = cityRepository.FindByName(toName);
if (notifiers != null)
{
notifiers(source, target);
}
List <City> cities = cityRepository.FindCitiesBetween(
source, target);
if (cities.Count < 1)
{
return(null);
}
List <City> Q = new List <City>();
Dictionary <City, Double> dist = new Dictionary <City, Double>();
Dictionary <City, City> previous = new Dictionary <City, City>();
foreach (City v in cities)
{
dist[v] = double.MaxValue;
previous[v] = null;
Q.Add(v);
}
dist[source] = 0.0;
while (Q.Count > 0)
{
City u = null;
double minDist = double.MaxValue;
// find city u with smallest dist
foreach (City c in Q)
{
if (dist[c] < minDist)
{
u = c;
minDist = dist[c];
}
}
if (u == null)
{
break;
}
Q.Remove(u);
foreach (City n in linkRepository.FindNeighbours(u, tmode))
{
Link l = linkRepository.FindLink(u, n, tmode);
double d = dist[u];
if (l != null)
{
d += l.Distance;
}
else
{
d += double.MaxValue;
}
if (dist.ContainsKey(n) && d < dist[n])
{
dist[n] = d;
previous[n] = u;
}
}
}
return(createItinerary(source, target, previous));
}
