DiagrammeR (version 0.9.2)

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, expressions, set_op = "union")

Arguments

graph

a graph object of class dgr_graph.

expressions

one or more expressions for filtering of nodes by degree values. Use a combination of a degree type (deg for total degree, indeg for in-degree, and outdeg for out-degree) with a comparison operator and values for comparison (e.g., use "deg >= 2" to select nodes with a degree greater than or equal to 2).

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

# NOT RUN {
# Create a random graph with a high amount
# of connectedness
graph <-
  create_random_graph(
    n = 35, m = 125,
    set_seed = 23)

# Report which nodes have a total degree (in-degree
# + out-degree) of exactly 9
graph %>%
  select_nodes_by_degree(
    expressions = "deg == 9") %>%
  get_selection()
#> [1]  2  9 10 14 17 19 31 33

# Report which nodes have a total degree greater
# than or equal to 9
graph %>%
  select_nodes_by_degree(
    expressions = "deg >= 9") %>%
  get_selection()
#> [1]  2  6  9 10 14 17 19 22 25 29 31 33

# 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)
graph %>%
  select_nodes_by_degree(
    expressions = "deg < 3") %>%
  select_nodes_by_degree(
    expressions = "deg > 10") %>%
  get_selection()
#> [1]  6 16 22

# 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)
graph %>%
  select_nodes_by_degree(
    expressions = "deg >= 3") %>%
  select_nodes_by_degree(
    expressions = "deg <= 10",
    set_op = "intersect") %>%
  get_selection()
#>  [1]  1  2  3  4  5  7  8  9 10 11 12 13 14
#> [14] 15 17 18 19 20 21 23 24 25 26 27 28 29
#> [28] 30 31 32 33 34 35

# Select all nodes with an in-degree greater than 5,
# then, apply a node attribute to those selected nodes
# (coloring the selected nodes red)
graph_2 <-
  graph %>%
  select_nodes_by_degree(
    expressions = "indeg > 5") %>%
  set_node_attrs_ws(
    node_attr = "color",
    value = "red")

# Get the selection of nodes
graph_2 %>%
  get_selection()
#> [1] 14 22 23 25 27 29 31 33 34
# }

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