Return root, end, or branchpoints of an igraph object

Source: R/graph-nodes.R

Return root, end, or branchpoints of an igraph object

graph.nodes(
  x,
  type = c("root", "end", "branch"),
  original.ids = "name",
  exclude.isolated = TRUE
)

Arguments

x

An ngraph or raw igraph object

type

one of root, end (which includes root) or branch

original.ids

Use named attribute to return original vertex ids (when available). Set to FALSE when this is not desired.

exclude.isolated

Do not count isolated vertices as root/end points (default)

Details

This function underlies rootpoints.igraph methods and friends. It is conceived of as slightly lower level and end users would normally use the rootpoints methods.

graph.nodes should work for any igraph object (including ngraph objects, which inherit from igraph). However the graph must be directed in order to return a root point

See also

rootpoints, ngraph

Examples

ng=as.ngraph(Cell07PNs[[1]])
# set some arbitrary vertex identifiers
igraph::vertex_attr(ng, 'name') <-sample(500, nvertices(ng))
# return those identifiers
graph.nodes(ng, type = 'end')
#>  [1] 440 270 349 424 390 380 453 215 271 195  50  11  65  80 316 214 319 138
# ... or raw vertex indices
graph.nodes(ng,type = 'end', original.ids = FALSE)
#>  [1]   1  42  59  62  80  85  96 100 102 112 117 121 134 148 154 165 172 180