DiagrammeR (version 0.7)

get_edges: Get node IDs associated with edges

Description

Provides information on the node IDs associated with edges from one or more edge data frames, or, a graph object.

Usage

get_edges(..., return_type = "list")

Arguments

...

a collection of edge data frames or graph objects.

return_type

using list (the default) will provide a list object containing vectors of outgoing and incoming node IDs associated with edges. With df, a data frame containing outgoing and incoming node IDs associated with edges. With vec

Value

• a list, data frame, or a vector object, depending on the value given to return_type.

Examples

# Before getting node ID values, create a simple graph
nodes <-
  create_nodes(nodes = LETTERS,
               label = TRUE,
               type = c(rep("a_to_g", 7),
                        rep("h_to_p", 9),
                        rep("q_to_x", 8),
                        rep("y_and_z",2)))

edges <-
  create_edges(from = sample(LETTERS, replace = TRUE),
               to = sample(LETTERS, replace = TRUE),
               label = "edge",
               relationship = "letter_to_letter")

graph <-
  create_graph(nodes_df = nodes,
               edges_df = edges,
               graph_attrs = "layout = neato",
               node_attrs = c("fontname = Helvetica",
                              "shape = circle"))

# Can get the 'outgoing' and 'incoming' node ID values
# in a list object
get_edges(graph, return_type = "list") # the default
#> [[1]]
#>  [1] "A" "H" "W" "U" "I" "M" "U" "T" "I" "R" "O"
#> [12] "G" "O" "A" "V" "I" "M" "K" "R" "T" "Y" "R"
#> [23] "M" "L" "H" "V"

#> [[2]]
#>  [1] "Z" "U" "O" "K" "V" "M" "N" "C" "D" "Z" "B"
#> [12] "G" "U" "Y" "H" "V" "R" "V" "Z" "S" "Q" "I"
#> [23] "P" "S" "E" "P"

# Similarly, you can specify that a data frame is given
get_edges(graph, return_type = "df")
#>    from to
#> 1     A  Z
#> 2     H  U
#> 3     W  O
#> 4     U  K
#> 5     I  V
#>..   ... ..

# A character string with node IDs can instead be gotten
get_edges(graph, return_type = "vector")
#>  [1] "A -> Z" "H -> U" "W -> O" "U -> K" "I -> V"
#>  [6] "M -> M" "U -> N" "T -> C" "I -> D" "R -> Z"
#> [11] "O -> B" "G -> G" "O -> U" "A -> Y" "V -> H"
#> [16] "I -> V" "M -> R" "K -> V" "R -> Z" "T -> S"
#> [21] "Y -> Q" "R -> I" "M -> P" "L -> S" "H -> E"
#> [26] "V -> P"