From a graph object of class
dgr_graph
, determine whether an edge
(defined by a pair of node IDs or node label
values) is present.
is_edge_present(graph, edge = NULL, from = NULL, to = NULL)
graph | a graph object of class
|
---|---|
edge | an edge ID value to test for
presence in the graph. If a single, numeric
value is provided then values for |
from | a node ID from which the edge
is outgoing, or, the label associated with
the node. For an undirected graph, the
value in |
to | a node ID to which the edge is
incoming, or, the label associated with
the node. For an undirected graph, the
value in |
a logical value.
# Create a simple graph with # a path of four nodes graph <- create_graph() %>% add_path( n = 4, type = "path", label = c("one", "two", "three", "four")) # Find out if edge ID `3` # is present in the graph graph %>% is_edge_present(edge = 3)#> [1] TRUE# Determine if there are any edges # with the definition `1` -> `2` graph %>% is_edge_present( from = 1, to = 2)#> [1] TRUE# Determine if there are any edges # with the definition `4` -> `5` graph %>% is_edge_present( from = 4, to = 5)#> [1] FALSE# Determine whether an edge, # defined by its labels as # `two` -> `three`, exists in # the graph graph %>% is_edge_present( from = "two", to = "three")#> [1] TRUE# Set the graph as undirected # and determine whether an # edge between nodes with labels # `three` and `two` exists graph %>% set_graph_undirected() %>% is_edge_present( from = "three", to = "two")#> [1] TRUE