--- a
+++ b/man/combine_layers.Rd
@@ -0,0 +1,67 @@
+% 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)
+
+
+}