DiagrammeR (version 0.8.1)

node_present: Determine whether a specified node is present in an existing graph object

Description

From a graph object of class dgr_graph, determine whether a specified node is present.

Usage

node_present(graph, node)

Arguments

graph

a graph object of class dgr_graph that is created using create_graph.

node

a value that may or may not match a node ID in the graph.

Value

• a logical value.

Examples

# Before finding out whether a particular node is present,
# 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",
               rel = "letter_to_letter")

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

# Verify that node with ID 'a' is not in graph
node_present(graph, "a")
#> FALSE

# Is node with ID 'A' in the graph?
node_present(graph, "A")
#> TRUE

# Are all node ID values from the LETTERS vector
in the graph?
all(sapply(LETTERS, function(x) node_present(graph, x)))
#> TRUE