Add new edges with identical definitions as with a selection of edges

Add edges in the same direction of one or more edges available as an edge selection in a graph object of class dgr_graph. New graph edges have the same edge definitions as those in the selection except with new edge ID values. There is also the option to assign a common rel grouping to the newly created edges. Upon addition of the edges, the edge selection will be retained for further selection or traversal operations.

This function makes use of an active selection of edges (and the function ending with _ws hints at this).

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().

Usage

add_forward_edges_ws(graph, rel = NULL)

Arguments

graph

A graph object of class dgr_graph.

rel

An optional string to apply a rel attribute to all newly created edges.

Value

A graph object of class dgr_graph.

See also

Other edge creation and removal: add_edge(), add_edge_clone(), add_edge_df(), add_edges_from_table(), add_edges_w_string(), add_reverse_edges_ws(), copy_edge_attrs(), create_edge_df(), delete_edge(), delete_edges_ws(), delete_loop_edges_ws(), drop_edge_attrs(), edge_data(), join_edge_attrs(), mutate_edge_attrs(), mutate_edge_attrs_ws(), recode_edge_attrs(), rename_edge_attrs(), rescale_edge_attrs(), rev_edge_dir(), rev_edge_dir_ws(), set_edge_attr_to_display(), set_edge_attrs(), set_edge_attrs_ws()

Examples

# Create an empty graph, add 2 nodes
# to it, and create the edge `1->2`
graph <-
  create_graph() %>%
  add_n_nodes(
    n = 2,
    type = "type_a",
    label = c("a_1", "a_2")) %>%
  add_edge(
    from = 1, to = 2, rel = "a")

# Get the graph's edges
graph %>% get_edge_ids()
#> [1] 1

# Select the edge and create 2
# additional edges with the same
# definition (`1->2`) but with
# different `rel` values (`b` and `c`)
graph <-
  graph %>%
  select_edges() %>%
  add_forward_edges_ws(rel = "b") %>%
  add_forward_edges_ws(rel = "c") %>%
  clear_selection()

# Get the graph's edge data frame
graph %>% get_edge_df()
#>   id from to rel
#> 1  1    1  2   a
#> 2  2    1  2   b
#> 3  3    1  2   c