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

Source: R/foreign.R
graph_from_graphdb.Rd

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

Usage

graph_from_graphdb(
  url = NULL,
  prefix = "iso",
  type = "r001",
  nodes = NULL,
  pair = "A",
  which = 0,
  base = "https://github.com/igraph/graphsdb/raw/refs/heads/main",
  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.

Value

A new graph object.

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 https://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.

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)

See also

read_graph(), isomorphic()

Foreign format readers read_graph(), write_graph()

Author

Gabor Csardi csardi.gabor@gmail.com