Learn R Programming

DiagrammeR (version 1.0.11)

get_edges: Get node IDs associated with edges

Description

Obtain a vector, data frame, or list of node IDs associated with edges in a graph object. An optional filter by edge attribute can limit the set of edges returned.

Usage

get_edges(
  graph,
  conditions = NULL,
  return_type = "vector",
  return_values = "id"
)

Value

A list, data frame, or a vector object, depending on the value given to return_type.

Arguments

graph

A graph object of class dgr_graph.

conditions

an option to use filtering conditions for the retrieval of edges.

return_type

using vector (the default), a vector of character objects representing the edges is provided. With list a list object will be provided that contains vectors of outgoing and incoming node IDs associated with edges. With df, a data frame containing outgoing and incoming node IDs associated with edges.

return_values

using id (the default) results in node ID values returned in the edge definitions. With label, the node labels will instead be used to define edges.

Examples

Run this code
# Create a node data frame (ndf)
ndf <-
  create_node_df(
    n = 4,
    label = c("one", "two", "three", "four"),
    type = "letter",
    color = c("red", "green", "grey", "blue"),
    value = c(3.5, 2.6, 9.4, 2.7))

# Create an edge data frame (edf)
edf <-
  create_edge_df(
    from = c(1, 2, 3),
    to = c(4, 3, 1),
    rel = "leading_to",
    color = c("pink", "blue", "blue"),
    value = c(3.9, 2.5, 7.3))

# Create a graph
graph <-
  create_graph(
    nodes_df = ndf,
    edges_df = edf)

# Get all edges within a graph, returned as a list
graph %>%
  get_edges(
    return_type = "vector")

# Get all edges within a graph, returned as a
# data frame
graph %>%
  get_edges(
    return_type = "df")

# Get all edges returned as a list
graph %>%
  get_edges(
    return_type = "list")

# Get a vector of edges using
# a numeric comparison (i.e.,
# all edges with a `value`
# attribute greater than 3)
graph %>%
  get_edges(
    conditions = value > 3,
    return_type = "vector")

# Get a vector of edges using
# a matching condition
graph %>%
  get_edges(
    conditions = color == "pink",
    return_type = "vector")

# Use multiple conditions to
# return edges with the
# desired attribute values
graph %>%
  get_edges(
    conditions =
      color == "blue" &
      value > 3,
    return_type = "vector")

# Use `return_values = "label"`
# to return the labels of the
# connected nodes
graph %>%
  get_edges(
    conditions =
      color == "blue" &
      value > 3,
    return_type = "vector",
    return_values = "label")

Run the code above in your browser using DataLab