DiagrammeR (version 0.7)

node_count: Get count of all nodes or certain types of nodes

Description

From a graph object of class dgr_graph, get a count of nodes in the graph and optionally obtain a count of nodes by their type.

Usage

node_count(graph, type = FALSE)

Arguments

graph

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

type

either a logical value, where TRUE provides a named vector of node count by type and FALSE (the default) provides a total count, or, a string corresponding to one or more node types.

Value

• a numeric vector of single length.

Examples

# Before getting counts of nodes, 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 counts of nodes grouped by the "type" attribute
node_count(graph, type = TRUE) # the default
#> a_to_g  h_to_p  q_to_x y_and_z
#>      7       9       8       2

# Get a total count of nodes with no grouping
node_count(graph, type = FALSE)
#> [1] 26