agopen: A function to obtain a libgraph object

In kasperdanielhansen/Rgraphviz: Provides plotting capabilities for R graph objects

A function to obtain a libgraph object

Description

This function will read in a graph object and create a Ragraph object, returning it for use in other functions. The graph represented by the Ragraph can be laidout in various formats.

Usage

agopen(graph, name, nodes, edges, kind = NULL, layout = TRUE,
       layoutType = "dot",
       attrs = list(), nodeAttrs = list(), edgeAttrs = list(),
       subGList = list(), edgeMode = edgemode(graph),
       recipEdges=c("combined", "distinct"))

Arguments

graph	An object of class graphNEL
nodes	A list of pNode objects
edges	A list of pEdge objects
name	The name of the graph
kind	The type of graph
layout	Whether to layout the graph or not
layoutType	Defines the layout engine. Defaults to dot, and see graphvizCapabilities()$layoutTypes for possible values.
attrs	A list of graphviz attributes
nodeAttrs	A list of specific node attributes
edgeAttrs	A list of specific edge attributes
subGList	A list describing subgraphs for the graph parameter
edgeMode	Whether the graph is directed or undirected
recipEdges	How to handle reciprocated edges, defaults to combined

Details

graph is from the package graph-class.

The user can specify either the graph parameter and/or a combination of nodes and edges. If either of the latter parameters are not specified then graph must be passed in, and is used in the functions buildNodeList and buildEdgeList (as appropriate - if nodes is passed in but edges is not, only buildEdgeList is called) which are default transformer functions to generate the pNode and pEdge lists for layout.

The edgeMode argument specifies whether the graph is to be laid out with directed or undirected edges. This parameter defaults to the edgemode of the graph argument - note that if graph was not passed in then edgeMode must be supplied.

The kind parameter works as follows:

NULL:

Determine the direction of the graph from the graph object. This is the default and the recommended method.

AGRAPH:

An undirected graph

AGDIGRAPH:

A directed graph

AGRAPHSTRICT:

A strict undirected graph

AGDIGRAPHSTRICT:

A strict directed graph

Strict graphs do not allow self arcs or multi-edges.

If layout is set to TRUE, then the libgraph routines are used to compute the layout locations for the graph. Otherwise the graph is returned without layout information.

The subGList parameter is a list describing any subgraphs, where each element represents a subgraph and is itself a list with up to three elements. The first element, graph is required and contains the actual graph object for the subgraph. The second element, cluster is a logical value indicating if this is a cluster or a subgraph (a value of TRUE indicates a cluster, which is also the default value if this element is not specified). In Graphviz, subgraphs are more of an organizational mechanism, whereas clusters are laid out separately from the main graph and then later inserted. The last element of the list, attrs is used if there are any attributes for this subgraph. This is a named vector where the names are the attributes and the elements are the values for those attributes.

For a description of attrs, nodeAttrs and edgeAttrs, see the Ragraph man page.

The recipEdges argument can be used to specify how to handle reciprocal edges. The default value, combined will combine any reciprocated edges into a single edge (and if the graph is directed, will by default place an arrowhead on both ends of the edge), while the other option is distinct which will draw to separate edges. Note that in the case of an undirected graph, every edge of a graphNEL is going to be reciprocal due to implementation issues.

Value

An object of class Ragraph

Author(s)

Jeff Gentry

References

http://www.research.att.com/sw/tools/graphviz/

See Also

graphLayout, Ragraph, plot

Examples

set.seed(123)
V <- letters[1:10]
M <- 1:4
g1 <- randomGraph(V, M, .2)
z <- agopen(g1,name="foo")
z
z <- agopen(g1,name="foo",layoutType="neato")

kasperdanielhansen/Rgraphviz documentation built on Nov. 4, 2022, 4:14 a.m.