% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/plot.common.R
\name{curve_multiple}
\alias{curve_multiple}
\title{Optimal edge curvature when plotting graphs}
\usage{
curve_multiple(graph, start = 0.5)
}
\arguments{
\item{graph}{The input graph.}

\item{start}{The curvature at the two extreme edges. All edges will have a
curvature between \code{-start} and \code{start}, spaced equally.}
}
\value{
A numeric vector, its length is the number of edges in the graph.
}
\description{
If graphs have multiple edges, then drawing them as straight lines does not
show them when plotting the graphs; they will be on top of each other. One
solution is to bend the edges, with diffenent curvature, so that all of them
are visible.
}
\details{
\code{curve_multiple()} calculates the optimal \code{edge.curved} vector for
plotting a graph with multiple edges, so that all edges are visible.
}
\section{Related documentation in the C library}{
\href{https://igraph.org/c/html/0.10.17/igraph-Structural.html#igraph_get_edgelist}{\code{get_edgelist()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Basic.html#igraph_vcount}{\code{vcount()}}
}

\examples{

g <- make_graph(c(
  0, 1, 1, 0, 1, 2, 1, 3, 1, 3, 1, 3,
  2, 3, 2, 3, 2, 3, 2, 3, 0, 1
) + 1)

curve_multiple(g)

set.seed(42)
plot(g)

}
\seealso{
\link{igraph.plotting} for all plotting parameters,
\code{\link[=plot.igraph]{plot.igraph()}}, \code{\link[=tkplot]{tkplot()}} and \code{\link[=rglplot]{rglplot()}}
for plotting functions.
}
\author{
Gabor Csardi \email{csardi.gabor@gmail.com}
}
\concept{plot.common}
\keyword{graphs}
