igraph: graph_from_graphdb – R documentation

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igraph

graph_from_graphdb

Load a graph from the graph database for testing graph isomorphism.

Description

This function downloads a graph from a database created for the evaluation of graph isomorphism testing algothitms.

Usage

graph_from_graphdb(
  url = NULL,
  prefix = "iso",
  type = "r001",
  nodes = NULL,
  pair = "A",
  which = 0,
  base = "http://cneurocvs.rmki.kfki.hu/graphdb/gzip",
  compressed = TRUE,
  directed = TRUE
)

Arguments

`url`	If not `NULL` it is a complete URL with the file to import.
`prefix`	Gives the prefix. See details below. Possible values: `iso`, `i2`, `si4`, `si6`, `mcs10`, `mcs30`, `mcs50`, `mcs70`, `mcs90`.
`type`	Gives the graph type identifier. See details below. Possible values: `r001`, `r005`, `r01`, `r02`, `m2D`, `m2Dr2`, `m2Dr4`, `m2Dr6` `m3D`, `m3Dr2`, `m3Dr4`, `m3Dr6`, `m4D`, `m4Dr2`, `m4Dr4`, `m4Dr6`, `b03`, `b03m`, `b06`, `b06m`, `b09`, `b09m`.
`nodes`	The number of vertices in the graph.
`pair`	Specifies which graph of the pair to read. Possible values: `A` and `B`.
`which`	Gives the number of the graph to read. For every graph type there are a number of actual graphs in the database. This argument specifies which one to read.
`base`	The base address of the database. See details below.
`compressed`	Logical constant, if TRUE than the file is expected to be compressed by gzip. If `url` is `NULL` then a ‘`.gz`’ suffix is added to the filename.
`directed`	Logical constant, whether to create a directed graph.

Details

graph_from_graphdb reads a graph from the graph database from an FTP or HTTP server or from a local copy. It has two modes of operation:

If the url argument is specified then it should the complete path to a local or remote graph database file. In this case we simply call read_graph with the proper arguments to read the file.

If url is NULL, and this is the default, then the filename is assembled from the base, prefix, type, nodes, pair and which arguments.

Unfortunately the original graph database homepage is now defunct, but see its old version at http://web.archive.org/web/20090215182331/http://amalfi.dis.unina.it/graph/db/doc/graphdbat.html for the actual format of a graph database file and other information.

Value

A new graph object.

Examples

g <- graph_from_graphdb(prefix="iso", type="r001", nodes=20, pair="A",
  which=10, compressed=TRUE)
g2 <- graph_from_graphdb(prefix="iso", type="r001", nodes=20, pair="B",
  which=10, compressed=TRUE)
graph.isomorphic.vf2(g, g2)	% should be TRUE
g3 <- graph_from_graphdb(url=paste(sep="/",
                              "http://cneurocvs.rmki.kfki.hu",
                              "graphdb/gzip/iso/bvg/b06m",
                              "iso_b06m_m200.A09.gz"))

Author(s)

Gabor Csardi csardi.gabor@gmail.com

References

M. De Santo, P. Foggia, C. Sansone, M. Vento: A large database of graphs and its use for benchmarking graph isomorphism algorithms, Pattern Recognition Letters, Volume 24, Issue 8 (May 2003)