makegraph.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/graphs.R
\name{makegraph}
\alias{makegraph}
\title{Construct graph}
\usage{
makegraph(
  df,
  directed = TRUE,
  coords = NULL,
  aux = NULL,
  capacity = NULL,
  alpha = NULL,
  beta = NULL
)
}
\arguments{
\item{df}{A data.frame or matrix containing 3 columns: from, to, cost. See details.}

\item{directed}{logical. If \code{FALSE}, then all edges are duplicated by inverting 'from' and 'to' nodes.}

\item{coords}{Optional. A data.frame or matrix containing all nodes coordinates. Columns order should be 'node_ID', 'X', 'Y'.}

\item{aux}{Optional. A vector or a single value describing an additional edge weight.}

\item{capacity}{Optional. A vector or a single value describing edge capacity. Used for traffic assignment.}

\item{alpha}{Optional. A vector or a single value describing alpha parameter. Used for traffic assignment.}

\item{beta}{Optional. A vector or a single value describing beta parameter. Used for traffic assignment.}
}
\value{
Named list with two useful attributes for the user : \cr

\emph{nbnode} : total number of vertices \cr
\emph{dict$ref} : vertices IDs
}
\description{
Construct graph
}
\details{
'from' and 'to' are character or numeric vector containing nodes IDs.
'cost' is a non-negative numeric vector describing the cost (e.g time, distance) between each 'from' and 'to' nodes.
\code{coords} should not be angles (e.g latitude and longitude), but expressed in a projection system.
\code{aux} is an additional weight describing each edge. Shortest paths are always computed using 'cost' but \code{aux} can be summed over shortest paths.
\code{capacity}, \code{alpha} and \code{beta} are parameters used in the Volume Delay Function (VDF) to equilibrate traffic in the network. See \link{assign_traffic}.
\code{capacity}, \code{alpha}, \code{beta} and \code{aux} must have a length equal to \code{nrow(df)}. If a single value is provided, this value is replicated for each edge.
\code{alpha} must be different from 0 and \code{alpha} must be greater or equal to 1.
For more details and examples about traffic assignment, please see the package website : \url{https://github.com/vlarmet/cppRouting/blob/master/README.md}
}
\examples{
#Data describing edges of the graph
edges<-data.frame(from_vertex=c(0,0,1,1,2,2,3,4,4),
                  to_vertex=c(1,3,2,4,4,5,1,3,5),
                  cost=c(9,2,11,3,5,12,4,1,6))

#Construct directed and undirected graph
directed_graph<-makegraph(edges,directed=TRUE)
non_directed<-makegraph(edges,directed=FALSE)

#Visualizing directed and undirected graphs
if(requireNamespace("igraph",quietly = TRUE)){
  plot(igraph::graph_from_data_frame(edges))
  plot(igraph::graph_from_data_frame(edges,directed=FALSE))
}

#Coordinates of each nodes
coord<-data.frame(node=c(0,1,2,3,4,5),X=c(2,2,2,0,0,0),Y=c(0,2,2,0,2,4))

#Construct graph with coordinates
directed_graph2<-makegraph(edges, directed=TRUE, coords=coord)

}