DiagrammeR: trav_reverse_edge – R documentation

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trav_reverse_edge

Traverse to any reverse edges

Description

From an active selection of edges in a graph object of class dgr_graph, traverse to any available reverse edges between the nodes common to the selected edges. For instance, if an active selection has the edge 1->2 but there is also an (not selected) edge 2->1, then this function can either switch to the selection of 2->1, or, incorporate both those edges into the active selection of edges.

Usage

trav_reverse_edge(graph, add_to_selection = FALSE)

Arguments

`graph`	A graph object of class `dgr_graph`.
`add_to_selection`	An option to either add the reverse edges to the active selection of edges (`TRUE`) or switch the active selection entirely to those reverse edges (`FALSE`, the default case).

Details

This traversal function makes use of an active selection of edges. After the traversal, depending on the traversal conditions, there will either be a selection of edges or no selection at all.

Selections of edges can be performed using the following selection (select_*()) functions: select_edges(), select_last_edges_created(), select_edges_by_edge_id(), or select_edges_by_node_id().

Selections of edges can also be performed using the following traversal (trav_*()) functions: trav_out_edge(), trav_in_edge(), trav_both_edge(), or trav_reverse_edge().

Value

A graph object of class dgr_graph.

Examples

# Create a node data frame (ndf)
ndf <-
  create_node_df(
    n = 4,
    type = "basic",
    label = TRUE)

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

# Create a graph with the
# ndf and edf
graph <-
  create_graph(
    nodes_df = ndf,
    edges_df = edf)

# Explicitly select the edges
# `1`->`4` and `2`->`3`
graph <-
  graph %>%
  select_edges(
    from = 1,
      to = 4) %>%
  select_edges(
    from = 2,
      to = 3)

# Get the inital edge selection
graph %>% get_selection()

# Traverse to the reverse edges
# (edges `2`: `4`->`1` and
# `4`:`3`->`2`)
graph <-
  graph %>%
  trav_reverse_edge()

# Get the current selection of edges
graph %>% get_selection()

DiagrammeR

Graph/Network Visualization

v1.0.6.1

MIT + file LICENSE

Authors

Richard Iannone [aut, cre] (<https://orcid.org/0000-0003-3925-190X>)

Initial release