DiagrammeR (version 1.0.10)

get_edge_attrs_ws: Get edge attribute values from a selection of edges

Description

From a graph object of class dgr_graph, get edge attribute values for one or more edges.

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

get_edge_attrs_ws(graph, edge_attr)

Value

A named vector of edge attribute values for the attribute given by edge_attr by edge.

Arguments

graph

A graph object of class dgr_graph.

edge_attr

the name of the attribute for which to get values.

Examples

# Create a simple graph where
# edges have an edge attribute
# named `value`
graph <-
  create_graph() %>%
  add_n_nodes(n = 4) %>%
  {
    edges <-
      create_edge_df(
        from = c(1, 2, 1, 4),
          to = c(2, 3, 4, 3),
         rel = "rel")
    add_edge_df(
      graph = .,
      edge_df = edges)
  } %>%
  set_edge_attrs(
    edge_attr = value,
    values = 1.6,
    from = 1,
      to = 2) %>%
  set_edge_attrs(
    edge_attr = value,
    values = 4.3,
    from = 1,
      to = 4) %>%
  set_edge_attrs(
    edge_attr = value,
    values = 2.9,
    from = 2,
      to = 3) %>%
  set_edge_attrs(
    edge_attr = value,
    values = 8.4,
    from = 4,
      to = 3)

# Select the edges defined as
# `1`->`3` and `2`->`3`
graph <-
  graph %>%
  select_edges(
    from = c(1, 2),
    to = c(2, 3))

# Get the edge attribute values
# for the `value` attribute, limited
# to the current edge selection
graph %>%
  get_edge_attrs_ws(
    edge_attr = value)