do_dfs: Use the depth-first search (dfs) algorithm

In DiagrammeR: Graph/Network Visualization

Use the depth-first search (dfs) algorithm

Description

With a chosen or random node serving as the starting point, perform a depth-first search of the whole graph and return the node ID values visited. The dfs algorithm differs from breadth-first search (bfs) in that dfs will follow tree branches as far as possible until terminating at leaf node (bfs traverses branches one level at a time).

Usage

do_dfs(graph, node = NULL, direction = "all")

Arguments

graph	A graph object of class dgr_graph.
node	An optional node ID value to specify a single starting point for the dfs. If not provided, a random node from the graph will be chosen.
direction	Using all (the default), the bfs will ignore edge direction while traversing through the graph. With out and ⁠in⁠, traversals between adjacent nodes will respect the edge direction.

Value

A vector containing node ID values for nodes visited during the depth-first search. The order of the node IDs corresponds to the order visited.

Examples

# Create a graph containing
# two balanced trees
graph <-
  create_graph() %>%
  add_balanced_tree(
    k = 2, h = 2) %>%
  add_balanced_tree(
  k = 3, h = 2)

# Perform a depth-first
# search of the graph,
# beginning at the root
# node `1` (the default
# `direction = "all"`
# doesn't take edge
# direction into account)
graph %>%
  do_dfs(node = 1)

# If not specifying a
# starting node, the function
# will begin the search
# from a random node
graph %>%
  do_dfs()

# It's also possible to
# perform dfs while taking
# into account edge direction;
# using `direction = "in"`
# causes the dfs routine to
# visit nodes along inward edges
graph %>%
  do_dfs(
    node = 1,
    direction = "in")

# Using `direction = "out"`
# results in the dfs moving
# along solely outward edges
graph %>%
  do_dfs(
    node = 1,
    direction = "out")

DiagrammeR documentation built on May 31, 2023, 6:14 p.m.