% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/combine_layers.R
\name{combine_layers}
\alias{combine_layers}
\title{Combine layers}
\usage{
combine_layers(graph1, graph2 = NULL, interaction.df = NULL)
}
\arguments{
\item{graph1}{an igraph object or list of igraph (\code{list.igraph}).}

\item{graph2}{an igraph object or list of igraph (\code{list.igraph}) with
the same length as \code{graph1}.}

\item{interaction.df}{(optional) a 2 colomns data.frame (from, to)
describing the edges between vertices from both graphs.}
}
\value{
a merged graph with both vertex attributes from graph1 and graph2.
}
\description{
Return a merged graph from two graph layers.
}
\details{
If \code{graph2} is a single graph, it will be merged to each element of
\code{graph1} (\code{igraph} or \code{list.igraph}).

If \code{graph2} is a list of graph (\code{list.igraph}), each element of
\code{graph1} and each element of \code{graph2} are merged in pairs.

Optionally, \code{interaction.df} should be provide if any vertex are shared
between graphs. It can also be used to extend the first graph.

In both scenarios, vertex attributes are kept. If a vertex attribute is
missing from graph1 or graph2, NULL value is added.
Otherwise, if there is an overlap between attribute values for the same
vertex, attribute from graph2 is dropped.
}
\examples{
# with single graphs
graph1 <- igraph::graph_from_data_frame(list(from = c('A', 'B'),
                                             to = c('B', 'C')),
                                        directed = FALSE)
graph2 <- igraph::graph_from_data_frame(list(from = c(1), 
                                             to = c(2)),
                                        directed = FALSE)
res <- combine_layers(graph1 = graph1,
                      graph2 = graph2)

# with list of graphs
graph1.list <- list(graph1, graph1)
graph2.list <- list(graph2, graph2)
class(graph1.list) <- class(graph2.list) <- 'list.igraph'

res <- combine_layers(graph1 = graph1.list, 
                      graph2 = graph2)
res <- combine_layers(graph1 = graph1.list, 
                      graph2 = graph2.list)

# with interaction dataframe
interaction.df1 <- as.data.frame(list(from = c('C', 'B'), to = c(1, 2)))
res <- combine_layers(graph1 = graph1.list, 
                      graph2 = graph2, 
                      interaction.df = interaction.df1)


}