DiagrammeR (version 0.8.2)

get_nodes: Get a vector of node ID values

Description

Obtain a vector of node ID values from a graph object or a node data frame. An optional filter by node attribute can limit the set of node ID values returned.

Usage

get_nodes(x, node_attr = NULL, match = NULL)

Arguments

x

either a graph object of class dgr_graph that is created using create_graph or a node data frame.

node_attr

an optional character vector of node attribute values for filtering the node ID values returned.

match

an option to provide a logical expression with a comparison operator (>, <, ==, or !=) followed by a number for numerical filtering, or, a character string for filtering the edges returned through string matching.

Value

a vector of node ID values.

Examples

## Not run: 
# # Before getting node ID values, create a simple graph
# nodes <-
#   create_nodes(nodes = c("a", "b", "c", "d"),
#                type = "letter",
#                color = c("red", "green", "grey", "blue"),
#                value = c(3.5, 2.6, 9.4, 2.7))
# 
# graph <-
#   create_graph(nodes_df = nodes)
# 
# # Get a vector of all nodes in a graph
# get_nodes(graph)
# #> [1] "a" "b" "c" "d"
# 
# # Get a vector of node ID values from a node data frame
# get_nodes(nodes)
# #> [1] "a" "b" "c" "d"
# 
# # Get a vector of node ID values using a numeric
# # comparison (i.e., all nodes with 'value' attribute
# # greater than 3)
# get_nodes(graph,
#           node_attr = "value",
#           match = "> 3")
# #> [1] "a" "c"
# 
# # Get a vector of node ID values using a match
# # pattern (i.e., all nodes with 'color' attribute
# # of "green")
# get_nodes(graph,
#           node_attr = "color",
#           match = "green")
# #> [1] "b"
# ## End(Not run)