Traverse from one or more selected nodes onto adjacent, outward edges
From a graph object of class dgr_graph move to outgoing edges from a
selection of one or more selected nodes, thereby creating a selection of
edges. An optional filter by edge attribute can limit the set of edges
traversed to.
trav_out_edge( graph, conditions = NULL, copy_attrs_from = NULL, copy_attrs_as = NULL )
graph |
A graph object of class |
conditions |
An option to use filtering conditions for the traversal. |
copy_attrs_from |
Providing a node attribute name will copy those node attribute values to the traversed edges. If the edge attribute already exists, the values will be merged to the traversed edges; otherwise, a new edge attribute will be created. |
copy_attrs_as |
If a node attribute name is provided in
|
This traversal function makes use of an active selection of nodes. After the traversal, depending on the traversal conditions, there will either be a selection of edges or no selection at all.
Selections of nodes can be performed using the following node selection
(select_*()) functions: select_nodes(), select_last_nodes_created(),
select_nodes_by_degree(), select_nodes_by_id(), or
select_nodes_in_neighborhood().
Selections of nodes can also be performed using the following traversal
(trav_*()) functions: trav_out(), trav_in(), trav_both(),
trav_out_node(), trav_in_node(), trav_out_until(), or
trav_in_until().
A graph object of class dgr_graph.
# Set a seed
suppressWarnings(RNGversion("3.5.0"))
set.seed(23)
# Create a simple graph
graph <-
create_graph() %>%
add_n_nodes(
n = 2,
type = "a",
label = c("asd", "iekd")) %>%
add_n_nodes(
n = 3,
type = "b",
label = c("idj", "edl", "ohd")) %>%
add_edges_w_string(
edges = "1->2 1->3 2->4 2->5 3->5",
rel = c(NA, "A", "B", "C", "D")) %>%
set_node_attrs(
node_attr = values,
values = c(2.3, 4.7, 9.4,
8.3, 6.3))
# Create a data frame with node ID values
# representing the graph edges (with `from`
# and `to` columns), and, a set of numeric values
df <-
data.frame(
from = c(1, 1, 2, 2, 3),
to = c(2, 3, 4, 5, 5),
values = round(rnorm(5, 5), 2))
# Join the data frame to the graph's internal
# edge data frame (edf)
graph <-
graph %>%
join_edge_attrs(
df = df)
# Show the graph's internal node data frame
graph %>% get_node_df()
# Show the graph's internal edge data frame
graph %>% get_edge_df()
# Perform a simple traversal from nodes to
# outbound edges with no conditions on the
# nodes traversed to
graph %>%
select_nodes_by_id(nodes = 1) %>%
trav_out_edge() %>%
get_selection()
# Traverse from node `1` to any outbound
# edges, filtering to those edges that have
# NA values for the `rel` edge attribute
graph %>%
select_nodes_by_id(nodes = 1) %>%
trav_out_edge(
conditions = is.na(rel)) %>%
get_selection()
# Traverse from node `3` to any outbound
# edges, filtering to those edges that have
# numeric values greater than `5.0` for
# the `rel` edge attribute
graph %>%
select_nodes_by_id(nodes = 3) %>%
trav_out_edge(
conditions = values > 5.0) %>%
get_selection()
# Traverse from node `1` to any outbound
# edges, filtering to those edges that
# have values equal to `A` for the `rel`
# edge attribute
graph %>%
select_nodes_by_id(nodes = 1) %>%
trav_out_edge(
conditions = rel == "A") %>%
get_selection()
# Traverse from node `2` to any outbound
# edges, filtering to those edges that
# have values in the set `B` and `C` for
# the `rel` edge attribute
graph %>%
select_nodes_by_id(nodes = 2) %>%
trav_out_edge(
conditions = rel %in% c("B", "C")) %>%
get_selection()
# Traverse from node `2` to any
# outbound edges, and use multiple
# conditions for the traversal
graph %>%
select_nodes_by_id(nodes = 2) %>%
trav_out_edge(
conditions =
rel %in% c("B", "C") &
values >= 5.0) %>%
get_selection()
# Traverse from node `2` to any
# outbound edges, and use multiple
# conditions
graph %>%
select_nodes_by_id(nodes = 2) %>%
trav_out_edge(
conditions =
rel %in% c("B", "C") |
values > 6.0) %>%
get_selection()
# Traverse from node `2` to any outbound
# edges, and use a regular expression as
# a filtering condition
graph %>%
select_nodes_by_id(nodes = 2) %>%
trav_out_edge(
conditions = grepl("B|C", rel)) %>%
get_selection()
# Perform a traversal from all nodes to
# their outgoing edges and, while doing
# so, copy the `label` node attribute
# to any of the nodes' incoming edges
graph <-
graph %>%
select_nodes() %>%
trav_out_edge(
copy_attrs_from = label)
# Show the graph's internal edge
# data frame after this change
graph %>% get_edge_df()Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.