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 nodes by degree values. Use a combination of 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

# Create a random graph using
# the add_gnm_graph() function
graph <-
create_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]  5 10 26 31

# Report which nodes have a
# total degree greater than or
# equal to 9
graph %>%
select_nodes_by_degree(
expressions = "deg >= 9") %>%
get_selection()
#>  [1]  1  2  4  5 10 12 18 25 26 31

# 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 will union the
# sets of nodes selected)
graph %>%
select_nodes_by_degree(
expressions = "deg < 3") %>%
select_nodes_by_degree(
expressions = "deg > 10") %>%
get_selection()
#> [1] 1 2

# 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]  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
#> [26] 28 29 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]  1  4 13 25 35