R/dijkstra.R

In marma330/RPG: Euclidean and Dijkstra Algorithms

#' Shortest Path 
#' 
#' @param graph is A data frame
#' @param initial_node is a number for starting nod 
#' @return  the shortest path between the selected nod and all other nods
#' @examples 
#' dijkstra (wiki_graph , 3)
#' dijkstra (wiki_graph , 5)
#' @references
#'(https://en.wikipedia.org/wiki/Dijkstra%27s algorithm)
#'@export 





dijkstra<-function(graph,initial_node)
{
unvisited_set<-unique(graph$v1) #in the graphic is like puting it to white/red
stopifnot((initial_node)< length(unvisited_set))
          

distance<-vector(length=6) #this is lil blue number in the visual one
distance[initial_node]<-0
distance[-initial_node]<-9999

while (length(unvisited_set)>0)
{

  
current<-unvisited_set[1] 
x<-graph[graph$v1==current,]

for (i in 1:nrow(x))
  {
      if  ((distance[current]+x$w[i]) < distance[x$v2[i]])
      {distance[x$v2[i]]<-(distance[current]+x$w[i])}
}

unvisited_set<-unvisited_set[-1]
}
return(distance)
}