% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/layout.R
\name{layout_with_dh}
\alias{layout_with_dh}
\alias{with_dh}
\title{The Davidson-Harel layout algorithm}
\usage{
layout_with_dh(
  graph,
  coords = NULL,
  maxiter = 10,
  fineiter = max(10, log2(vcount(graph))),
  cool.fact = 0.75,
  weight.node.dist = 1,
  weight.border = 0,
  weight.edge.lengths = edge_density(graph)/10,
  weight.edge.crossings = 1 - sqrt(edge_density(graph)),
  weight.node.edge.dist = 0.2 * (1 - edge_density(graph))
)

with_dh(...)
}
\arguments{
\item{graph}{The graph to lay out. Edge directions are ignored.}

\item{coords}{Optional starting positions for the vertices. If this argument
is not \code{NULL} then it should be an appropriate matrix of starting
coordinates.}

\item{maxiter}{Number of iterations to perform in the first phase.}

\item{fineiter}{Number of iterations in the fine tuning phase.}

\item{cool.fact}{Cooling factor.}

\item{weight.node.dist}{Weight for the node-node distances component of the
energy function.}

\item{weight.border}{Weight for the distance from the border component of
the energy function. It can be set to zero, if vertices are allowed to sit
on the border.}

\item{weight.edge.lengths}{Weight for the edge length component of the
energy function.}

\item{weight.edge.crossings}{Weight for the edge crossing component of the
energy function.}

\item{weight.node.edge.dist}{Weight for the node-edge distance component of
the energy function.}

\item{...}{Passed to \code{layout_with_dh()}.}
}
\value{
A matrix with two columns, containing the x and y coordinates
of the vertices:
\describe{
\item{x}{
The x-coordinate of the vertex.
}
\item{y}{
The y-coordinate of the vertex.
}
}
}
\description{
Place vertices of a graph on the plane, according to the simulated annealing
algorithm by Davidson and Harel.
}
\details{
This function implements the algorithm by Davidson and Harel, see Ron
Davidson, David Harel: Drawing Graphs Nicely Using Simulated Annealing. ACM
Transactions on Graphics 15(4), pp. 301-331, 1996.

The algorithm uses simulated annealing and a sophisticated energy function,
which is unfortunately hard to parameterize for different graphs. The
original publication did not disclose any parameter values, and the ones
below were determined by experimentation.

The algorithm consists of two phases, an annealing phase, and a fine-tuning
phase. There is no simulated annealing in the second phase.

Our implementation tries to follow the original publication, as much as
possible. The only major difference is that coordinates are explicitly kept
within the bounds of the rectangle of the layout.
}
\section{Related documentation in the C library}{
\href{https://igraph.org/c/html/0.10.17/igraph-Layout.html#igraph_layout_davidson_harel}{\code{layout_davidson_harel()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Basic.html#igraph_vcount}{\code{vcount()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Structural.html#igraph_density}{\code{density()}}
}

\examples{

set.seed(42)
## Figures from the paper
g_1b <- make_star(19, mode = "undirected") + path(c(2:19, 2)) +
  path(c(seq(2, 18, by = 2), 2))
plot(g_1b, layout = layout_with_dh)

g_2 <- make_lattice(c(8, 3)) + edges(1, 8, 9, 16, 17, 24)
plot(g_2, layout = layout_with_dh)

g_3 <- make_empty_graph(n = 70)
plot(g_3, layout = layout_with_dh)

g_4 <- make_empty_graph(n = 70, directed = FALSE) + edges(1:70)
plot(g_4, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_5a <- make_ring(24)
plot(g_5a, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_5b <- make_ring(40)
plot(g_5b, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_6 <- make_lattice(c(2, 2, 2))
plot(g_6, layout = layout_with_dh)

g_7 <- graph_from_literal(1:3:5 - -2:4:6)
plot(g_7, layout = layout_with_dh, vertex.label = V(g_7)$name)

g_8 <- make_ring(5) + make_ring(10) + make_ring(5) +
  edges(
    1, 6, 2, 8, 3, 10, 4, 12, 5, 14,
    7, 16, 9, 17, 11, 18, 13, 19, 15, 20
  )
plot(g_8, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_9 <- make_lattice(c(3, 2, 2))
plot(g_9, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_10 <- make_lattice(c(6, 6))
plot(g_10, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_11a <- make_tree(31, 2, mode = "undirected")
plot(g_11a, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_11b <- make_tree(21, 4, mode = "undirected")
plot(g_11b, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)

g_12 <- make_empty_graph(n = 37, directed = FALSE) +
  path(1:5, 10, 22, 31, 37:33, 27, 16, 6, 1) + path(6, 7, 11, 9, 10) + path(16:22) +
  path(27:31) + path(2, 7, 18, 28, 34) + path(3, 8, 11, 19, 29, 32, 35) +
  path(4, 9, 20, 30, 36) + path(1, 7, 12, 14, 19, 24, 26, 30, 37) +
  path(5, 9, 13, 15, 19, 23, 25, 28, 33) + path(3, 12, 16, 25, 35, 26, 22, 13, 3)
plot(g_12, layout = layout_with_dh, vertex.size = 5, vertex.label = NA)
}
\references{
Ron Davidson, David Harel: Drawing Graphs Nicely Using Simulated
Annealing. \emph{ACM Transactions on Graphics} 15(4), pp. 301-331, 1996.
}
\seealso{
\code{\link[=layout_with_fr]{layout_with_fr()}},
\code{\link[=layout_with_kk]{layout_with_kk()}} for other layout algorithms.

Other graph layouts: 
\code{\link{add_layout_}()},
\code{\link{component_wise}()},
\code{\link{layout_}()},
\code{\link{layout_as_bipartite}()},
\code{\link{layout_as_star}()},
\code{\link{layout_as_tree}()},
\code{\link{layout_in_circle}()},
\code{\link{layout_nicely}()},
\code{\link{layout_on_grid}()},
\code{\link{layout_on_sphere}()},
\code{\link{layout_randomly}()},
\code{\link{layout_with_fr}()},
\code{\link{layout_with_gem}()},
\code{\link{layout_with_graphopt}()},
\code{\link{layout_with_kk}()},
\code{\link{layout_with_lgl}()},
\code{\link{layout_with_mds}()},
\code{\link{layout_with_sugiyama}()},
\code{\link{merge_coords}()},
\code{\link{norm_coords}()},
\code{\link{normalize}()}
}
\author{
Gabor Csardi \email{csardi.gabor@gmail.com}
}
\concept{graph layouts}
