DiagrammeR (version 0.8.4)

create_graph: Create a graph object

Description

Generates a graph object with the option to use node data frames (ndfs) and/or edge data frames (edfs) to populate the initial graph.

Usage

create_graph(nodes_df = NULL, edges_df = NULL, graph_attrs = NULL, node_attrs = NULL, edge_attrs = NULL, directed = TRUE, graph_name = NULL, graph_time = NULL, graph_tz = NULL, generate_dot = TRUE)

Arguments

nodes_df

an optional data frame containing, at minimum, a column (called nodes) which contains node IDs for the graph. Additional columns (named as Graphviz node attributes) can be included with values for the named node attribute.

edges_df

an optional data frame containing, at minimum, two columns (called from and to) where node IDs are provided. Additional columns (named as Graphviz edge attributes) can be included with values for the named edge attribute.

graph_attrs

an optional vector of graph attribute statements that can serve as defaults for the graph.

node_attrs

an optional vector of node attribute statements that can serve as defaults for nodes.

edge_attrs

an optional vector of edge attribute statements that can serve as defaults for edges.

directed

with TRUE (the default) or FALSE, either directed or undirected edge operations will be generated, respectively.

graph_name

an optional string for labeling the graph object.

graph_time

a date or date-time string (required for insertion of graph into a graph series of the type temporal).

graph_tz

an optional value for the time zone (tz) corresponding to the date or date-time string supplied as a value to graph_time. If no time zone is provided then it will be set to GMT.

generate_dot

an option to generate Graphviz DOT code and place into the graph object.

Value

a graph object of class dgr_graph.

Examples

# Create an empty graph
graph <- create_graph()

# A graph can be created with nodes and
# without edges; this is usually done in 2 steps:
# 1. create a node data frame (ndf) using the
#    `create_nodes()` function
nodes <-
  create_nodes(
    nodes = c("a", "b", "c", "d"))

# 2. create the graph object with `create_graph()`
#    and pass in the ndf to `nodes_df`
graph <- create_graph(nodes_df = nodes)

# You can create a similar graph with just nodes but
# also provide a range of attributes for the nodes
# (e.g., types, labels, arbitrary 'values')
nodes <-
  create_nodes(
    nodes = c("a", "b", "c", "d"),
    label = TRUE,
    type = c("type_1", "type_1",
             "type_5", "type_2"),
    shape = c("circle", "circle",
              "rectangle", "rectangle"),
    values = c(3.5, 2.6, 9.4, 2.7))

graph <- create_graph(nodes_df = nodes)

# A graph can also be created by just specifying the
# edges between nodes (in this case the unique set
# of nodes will be created added along with their
# connections but there is no possibility to add
# node attributes this way--they can be added later
# with different function--although edge attributes
# can specified); this is usually done in 2 steps:
# 1. create an edge data frame (edf) using the
#    `create_edges()` function:
edges <-
  create_edges(
    from = c("a", "b", "c"),
    to = c("d", "c", "a"),
    rel = "leading_to",
    values = c(7.3, 2.6, 8.3))

# 2. create the graph object with `create_graph()`
#    and pass in the edf to `edges_df`
graph <- create_graph(edges_df = edges)

# You can create a graph with both nodes and nodes
# defined, and, also add in some default attributes
# to be applied to all the nodes (`node_attrs`) and
# edges (`edge_attrs`) in this initial graph
graph <-
  create_graph(
    nodes_df = nodes,
    edges_df = edges,
    node_attrs = "fontname = Helvetica",
    edge_attrs = c("color = blue",
                   "arrowsize = 2"))