DiagrammeR (version 0.7)

get_predecessors: Get node IDs for predecessor nodes to the specified node

Description

Provides a vector of node IDs for all nodes that have a link to the given node.

Usage

get_predecessors(graph, node)

Arguments

graph

a graph object of class dgr_graph.

node

a node ID for the selected node.

Value

• a vector of node ID values.

Examples

# Before getting node ID values for predecessors of
# a specified node, 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"))

# Get predecessors for node "Z" in the graph
get_predecessors(graph, node = "Z")
#> [1] "A" "R" "R"

# If there are no predecessors, NA is returned
get_predecessors(graph, node = "A")
#> [1] NA