1% Generated by roxygen2: do not edit by hand 2% Please edit documentation in R/is_edge_present.R 3\name{is_edge_present} 4\alias{is_edge_present} 5\title{Determine whether a specified edge is present} 6\usage{ 7is_edge_present(graph, edge = NULL, from = NULL, to = NULL) 8} 9\arguments{ 10\item{graph}{A graph object of class \code{dgr_graph}.} 11 12\item{edge}{An edge ID value to test for presence in the graph. If a single, 13numeric value is provided then values for \code{from} or \code{to} needn't be 14supplied.} 15 16\item{from}{A node ID from which the edge is outgoing, or, the label 17associated with the node. For an undirected graph, the value in \code{from} can 18be interchangeable with that in \code{to}.} 19 20\item{to}{A node ID to which the edge is incoming, or, the label associated 21with the node. For an undirected graph, the value in \code{to} can be 22interchangeable with that in \code{from}.} 23} 24\value{ 25A logical value. 26} 27\description{ 28From a graph object of class \code{dgr_graph}, determine whether an edge (defined 29by a pair of node IDs or node label values) is present. 30} 31\examples{ 32# Create a simple graph with 33# a path of four nodes 34graph <- 35 create_graph() \%>\% 36 add_path( 37 n = 4, 38 type = "path", 39 label = c("one", "two", 40 "three", "four")) 41 42# Find out if edge ID `3` 43# is present in the graph 44graph \%>\% 45 is_edge_present(edge = 3) 46 47# Determine if there are any edges 48# with the definition `1` -> `2` 49graph \%>\% 50 is_edge_present( 51 from = 1, 52 to = 2) 53 54# Determine if there are any edges 55# with the definition `4` -> `5` 56graph \%>\% 57 is_edge_present( 58 from = 4, 59 to = 5) 60 61# Determine whether an edge, 62# defined by its labels as 63# `two` -> `three`, exists in 64# the graph 65graph \%>\% 66 is_edge_present( 67 from = "two", 68 to = "three") 69 70# Set the graph as undirected 71# and determine whether an 72# edge between nodes with labels 73# `three` and `two` exists 74graph \%>\% 75 set_graph_undirected() \%>\% 76 is_edge_present( 77 from = "three", 78 to = "two") 79 80} 81