DiagrammeR (version 0.8.2)

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

## Not run: 
# # 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
# ## End(Not run)