DiagrammeR (version 0.8.4)

select_nodes_by_degree: Select nodes in the graph based on their degree values

Description

Using a graph object of class dgr_graph, create a selection of nodes that have certain degree values.

Usage

select_nodes_by_degree(graph, degree_type, degree_values, set_op = "union")

Arguments

graph

a graph object of class dgr_graph that is created using create_graph.

degree_type

the type of degree, either: in for the indegree, out for the outdegree, and both or degree for the total degree (i.e., indegree + outdegree).

degree_values

a logical expression with a comparison operator (>, >=, <, <=< code="">, ==, or !=) followed by a number for numerical filtering.

set_op

the set operation to perform upon consecutive selections of graph nodes. This can either be as a union (the default), as an intersection of selections with intersect, or, as a difference on the previous selection, if it exists.

Value

a graph object of class dgr_graph.

Examples

library(magrittr)

# Create a random graph with a high amount
# of connectedness
random_graph <-
  create_random_graph(
    n = 35, m = 125,
    fully_connected = TRUE,
    directed = TRUE,
    set_seed = 25) %>%
  set_global_graph_attrs(
    'graph', 'layout', 'neato') %>%
  set_global_graph_attrs(
    'graph', 'overlap', 'false')

# Report which nodes have a total degree (indegree
# + outdegree) of exactly 9
random_graph %>%
  select_nodes_by_degree('both', '==9') %>%
  get_selection
#> $nodes
#> [1] "4"  "8"  "11" "18" "20" "24" "31"

# Report which nodes have a total degree greater
# than or equal to 9
random_graph %>%
  select_nodes_by_degree('both', '>=9') %>%
  get_selection
#> $nodes
#>  [1] "4"  "5"  "7"  "8"  "9"  "11" "18" "20" "24"
#> [10] "31" "32"

# Combine two calls of `select_nodes_by_degree()`
# to get those nodes with total degree less than 3
# and total degree greater than 10 (by default,
# those `select...()` functions `union` the sets of
# nodes selected)
random_graph %>%
  select_nodes_by_degree('both', '<3') %>%
  select_nodes_by_degree('both', '>10') %>%
  get_selection
#> $nodes
#> [1] "16" "5"  "7"

# Combine two calls of `select_nodes_by_degree()`
# to get those nodes with total degree greater than
# or equal to 3 and less than or equal to 10 (the
# key here is to `intersect` the sets of nodes
# selected in the second call)
random_graph %>%
  select_nodes_by_degree('both', '>=3') %>%
  select_nodes_by_degree('both', '<=10', 'intersect') %>%
  get_selection
#> $nodes
#> [1] "1"  "2"  "3"  "4"  "6"  "8"  "9"  "11" "13"
#> [10] "14" "15" "17" "18" "19" "20" "21" "22" "24"
#> [19] "25" "26" "27" "28" "29" "30" "31" "32" "33"
#> [28] "34" "35" "12" "23" "10"

# Select all nodes with an indegree greater than 5,
# then, apply a node attribute to those selected nodes
# (coloring the selected nodes red)
random_graph_2 <-
  random_graph %>%
  select_nodes_by_degree('in', '>5') %>%
  set_node_attrs_ws(
    node_attr = 'color', value = 'red')

# Get the selection of nodes
random_graph_2 %>% get_selection
#> $nodes
#> [1] "4" "6"