DiagrammeR (version 0.8.4)

get_edge_attrs: Get edge attribute values

Description

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

Usage

get_edge_attrs(x, edge_attr, from = NULL, to = NULL)

Arguments

x

either a graph object of class dgr_graph that is created using create_graph, or an edge data frame.

edge_attr

the name of the attribute for which to get values.

from

an optional vector of node IDs from which the edge is outgoing for filtering the list of edges.

to

an optional vector of node IDs from which the edge is incoming for filtering the list of edges.

Value

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

Examples

library(magrittr)

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

# Get the values for the `value` edge attribute
graph %>% get_edge_attrs(edge_attr = "value")
#> 1 -> 2 2 -> 3 1 -> 4 4 -> 3
#> 1.6    2.9    4.3    8.4

# To only return edge attribute values for specified
# edges, use the `from` and `to` arguments
graph %>% get_edge_attrs("value", c(1, 2), c(2, 3))
#> 1 -> 2 2 -> 3
#> 1.6    2.9