DiagrammeR (version 0.8.4)

node_type: Create, read, update, delete, or report status of a node type definition

Description

From a graph object of class dgr_graph, query a node in the graph (using the node ID) and perform operations on the type definition for that node.

Usage

node_type(graph, node, action = "read", value = NULL)

Arguments

graph

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

node

a node ID corresponding to the node to be selected.

action

the operation to perform on the node's type attribute. To remove the type definition from a node, use either delete, remove, or drop. To add a type definition to a node with no type set, use add or create. To update a node's type definition, use update. To return the value of a node type, use read. To determine whether there is a type set for the selected node, use check.

value

a string denoting the node type, to be supplied when either adding or updating a node type definition.

Value

a graph object of class dgr_graph.

Examples

library(magrittr)

# Create a node data frame (ndf)
nodes <-
  create_nodes(
    nodes = 1:5,
    type = c("a", "b", "c", "a", "c"))

# Create an edge data frame (edf)
edges <-
  create_edges(
    from = c(1, 3, 5, 2, 4),
    to = c(2, 2, 4, 4, 3))

# Create a graph
graph <-
  create_graph(nodes_df = nodes,
               edges_df = edges)

# Read the node `type` for node `1`
graph %>%
  node_type(1)
#> [1] "a"

# Remove the `type` value entirely from
# node `1`
graph %<>%
  node_type(1, "delete")

# Check that node `1` no longer has a
# `type` assignment
graph %>%
  node_type(1, "check")
#> [1] FALSE

# Add the `type` value "b" to node `1`
graph %<>%
  node_type(1, "add", "b")

# Read the node `type` for node `1`
graph %>%
  node_type(1)
#> [1] "b"

# Perform an in-place update of the `type`
# value for node `1` ("b" to "a")
graph %<>%
  node_type(1, "update", "a")

# Read the node `type` for node `1` to ensure
# that the change was made
graph %>%
  node_type(1)
#> [1] "a"