DiagrammeR: delete_edge – R documentation

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delete_edge

Delete an edge from an existing graph object

Description

From a graph object of class dgr_graph, delete an existing edge by specifying either: (1) a pair of node IDs corresponding to the edge (keeping into consideration the direction of the edge in a directed graph), or (2) an edge ID.

Usage

delete_edge(graph, from = NULL, to = NULL, id = NULL)

Arguments

`graph`	A graph object of class `dgr_graph`.
`from`	a node ID from which the edge to be removed is outgoing. If an edge ID is provided to `id`, then this argument is ignored. There is the option to use a node `label` value here (and this must correspondingly also be done for the `to` argument) for defining node connections. Note that this is only possible if all nodes have distinct `label` values set and none exist as an empty string.
`to`	a node ID to which the edge to be removed is incoming. If an edge ID is provided to `id`, then this argument is ignored. There is the option to use a node `label` value here (and this must correspondingly also be for the `from` argument) for defining node connections. Note that this is only possible if all nodes have distinct `label` values set and none exist as an empty string.
`id`	an edge ID of the edge to be removed.

Value

A graph object of class dgr_graph.

Examples

# Create a graph with 2 nodes
graph <-
  create_graph() %>%
  add_n_nodes(n = 2)

# Add an edge
graph <-
  graph %>%
  add_edge(
    from = 1,
    to = 2)

# Delete the edge
graph <-
  graph %>%
  delete_edge(
    from = 1,
    to = 2)

# Get the count of edges in the graph
graph %>% count_edges()

# Create an undirected graph with
# 2 nodes and an edge
graph_undirected <-
  create_graph(directed = FALSE) %>%
  add_n_nodes(n = 2) %>%
  add_edge(
    from = 1,
    to = 2)

# Delete the edge; the order of node ID
# values provided in `from` and `to`
# don't matter for the undirected case
graph_undirected %>%
  delete_edge(
    from = 2,
    to = 1) %>%
  count_edges()

# The undirected graph has a single
# edge with ID `1`; it can be
# deleted by specifying `id`
graph_undirected %>%
  delete_edge(id = 1) %>%
  count_edges()

# Create a directed graph with 2
# labeled nodes and an edge
graph_labeled_nodes <-
  create_graph() %>%
  add_n_nodes(
    n = 2,
    label = c("one", "two")) %>%
  add_edge(
    from = "one",
    to = "two")

# Delete the edge using the node
# labels in `from` and `to`; this
# is analogous to creating the
# edge using node labels
graph_labeled_nodes %>%
  delete_edge(
    from = "one",
    to = "two") %>%
  count_edges()

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