write_graph: Writing the graph to a file in some format

In igraph/rigraph: Network Analysis and Visualization

Writing the graph to a file in some format

Description

write_graph() is a general function for exporting graphs to foreign file formats. The recommended formats for data exchange are GraphML and GML.

Usage

write_graph(
  graph,
  file,
  format = c("edgelist", "pajek", "ncol", "lgl", "graphml", "dimacs", "gml", "dot",
    "leda"),
  ...
)

Arguments

graph	The graph to export.
file	A connection or a string giving the file name to write the graph to.
format	Character string giving the file format. Right now pajek, graphml, dot, gml, edgelist, lgl, ncol, leda and dimacs are implemented. As of igraph 0.4 this argument is case insensitive.
...	Other, format specific arguments, see below.

Value

A 'NULL“, invisibly.

Edge list format

The edgelist format is a simple text file, with one edge per line, the two zero-based numerical vertex IDs separated by a space character. Note that vertices are indexed starting with zero. The file is sorted by the first and the second column. This format has no additional arguments.

NCOL format

This format is a plain text edge list in which vertices are referred to by name rather than numerical ID. Edge weights may be optionally written. Additional parameters:

names

The name of a vertex attribute to take vertex names from or NULL to use zero-based numerical IDs.

weights

The name of an edge attribute to take edge weights from or NULL to omit edge weights.

Pajek format

The pajek format is provided for interoperability with the Pajek software only. Since the format does not have a formal specification, it is not recommended for general data exchange or archival.

Related documentation in the C library

igraph_write_graph_dimacs_flow(), igraph_write_graph_dot(), igraph_write_graph_edgelist(), igraph_write_graph_gml(), igraph_write_graph_graphml(), igraph_write_graph_leda(), igraph_write_graph_lgl(), igraph_write_graph_ncol(), igraph_write_graph_pajek().

Author(s)

Gabor Csardi [e-mail]

References

Adai AT, Date SV, Wieland S, Marcotte EM. LGL: creating a map of protein function with an algorithm for visualizing very large biological networks. J Mol Biol. 2004 Jun 25;340(1):179-90.

See Also

read_graph()

Foreign format readers graph_from_graphdb(), read_graph()

Examples

g <- make_ring(10)
file <- tempfile(fileext = ".txt")
write_graph(g, file, "edgelist")
if (!interactive()) {
  unlink(file)
}

igraph/rigraph documentation built on Feb. 5, 2025, 6:29 p.m.