% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/layout.R
\name{layout_nicely}
\alias{layout_nicely}
\alias{nicely}
\title{Choose an appropriate graph layout algorithm automatically}
\usage{
layout_nicely(graph, dim = 2, ...)

nicely(...)
}
\arguments{
\item{graph}{The input graph}

\item{dim}{Dimensions, should be 2 or 3.}

\item{\dots}{For \code{layout_nicely()} the extra arguments are passed to
the real layout function. For \code{nicely()} all argument are passed to
\code{layout_nicely()}.}
}
\value{
A numeric matrix with two or three columns.
}
\description{
This function tries to choose an appropriate graph layout algorithm for the
graph, automatically, based on a simple algorithm. See details below.
}
\details{
\code{layout_nicely()} tries to choose an appropriate layout function for the
supplied graph, and uses that to generate the layout. The current
implementation works like this:
\enumerate{
\item If the graph has a graph attribute called \sQuote{layout},
then this is used. If this attribute is an R function, then it is called, with the graph and any other extra arguments.

\item Otherwise, if the graph has vertex attributes called \sQuote{x} and
\sQuote{y}, then these are used as coordinates. If the graph has an
additional \sQuote{z} vertex attribute, that is also used.

\item Otherwise, if the graph is a forest and has less than 30 vertices, \code{layout_as_tree()} is used.

\item Otherwise,
if the graph is connected and has less than 1000 vertices, the
Fruchterman-Reingold layout is used, by calling \code{layout_with_fr()}.
\item Otherwise the DrL layout is used, \code{layout_with_drl()} is called.  }

In layout algorithm implementations, an argument named \sQuote{weights} is
typically used to specify the weights of the edges if the layout algorithm
supports them. In this case, omitting \sQuote{weights} or setting it to
\code{NULL} will make igraph use the 'weight' edge attribute from the graph
if it is present. However, most layout algorithms do not support non-positive
weights, so \code{layout_nicely()} would fail if you simply called it on
your graph without specifying explicit weights and the weights happened to
include non-positive numbers. We strive to ensure that \code{layout_nicely()}
works out-of-the-box for most graphs, so the rule is that if you omit
\sQuote{weights} or set it to \code{NULL} and \code{layout_nicely()} would
end up calling \code{layout_with_fr()} or \code{layout_with_drl()}, we do not
forward the weights to these functions and issue a warning about this. You
can use \code{weights = NA} to silence the warning.
}
\section{Related documentation in the C library}{
\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-Layout.html#igraph_layout_align}{\code{layout_align()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Structural.html#igraph_is_forest}{\code{is_forest()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Basic.html#igraph_edges}{\code{edges()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Basic.html#igraph_get_eids}{\code{get_eids()}}, \href{https://igraph.org/c/html/0.10.17/igraph-Basic.html#igraph_ecount}{\code{ecount()}}
}

\seealso{
\code{\link[=plot.igraph]{plot.igraph()}}

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_on_grid}()},
\code{\link{layout_on_sphere}()},
\code{\link{layout_randomly}()},
\code{\link{layout_with_dh}()},
\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}
\keyword{graphs}
