R/dijkstra.R

In OmidLavakhamseh/lab03: Greatest Common Divisor and Shortest Path

#' dijkstra which calculates the shortest path from initial node in a graph.
#' @author Hamed
#' @description recieve graph and initial node and calculate shortest path.
#' @export dijkstra
#' @import igraph
#' @importFrom graphics par
#' @param graph data frame
#' @param init_node number
#' @references \url{https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm}
#' @return dijkstra(graph,init_node)
#' @seealso \url{https://en.wikipedia.org/wiki/Graph_(mathematics}
#' @title dijkstra
#' @usage dijkstra(graph,init_node)


dijkstra <- function(graph,init_node){
  set.seed(500)
  el <- matrix(c(graph$v1,graph$v2), ncol=2)
  g <- igraph::graph_from_edgelist(el)
  oldpar <- par(mar = c(1,1,1,1))
  plot(g, edge.label = graph$w)
  par(oldpar)
  graph1 <- graph[!duplicated(graph$v1), ]
  g2 <- igraph::add_edges(igraph::make_empty_graph(length(graph1$w)), t(el[,1:2]), weight=graph$w)
  distances <- igraph::distances(g2, mode="out")
  distances[,init_node]
}