Combine two graphs in order to make a new graph.

## Arguments

- x
A

`DiagrammeR`

graph object to which another graph will be unioned. This graph should be considered the graph from which global graph attributes will be inherited in the resulting graph.- y
A

`DiagrammeR`

graph object that is to be unioned with the graph supplied as`x`

.

## Examples

```
# Create a graph with a cycle
# containing 6 nodes
graph_cycle <-
create_graph() %>%
add_cycle(n = 6)
# Create a random graph with
# 8 nodes and 15 edges using the
# `add_gnm_graph()` function
graph_random <-
create_graph() %>%
add_gnm_graph(
n = 8,
m = 15,
set_seed = 23)
# Combine the two graphs in a
# union operation
combined_graph <-
combine_graphs(
graph_cycle,
graph_random)
# Get the number of nodes in
# the combined graph
combined_graph %>% count_nodes()
#> [1] 14
# The `combine_graphs()`
# function will renumber
# node ID values in graph `y`
# during the union; this ensures
# that node ID values are unique
combined_graph %>% get_node_ids()
#> [1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14
```