igraph: read_graph – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

read_graph

Reading foreign file formats

Description

The read_graph function is able to read graphs in various representations from a file, or from a http connection. Various formats are supported.

Usage

read_graph(
  file,
  format = c("edgelist", "pajek", "ncol", "lgl", "graphml", "dimacs", "graphdb", "gml",
    "dl"),
  ...
)

Arguments

`file`	The connection to read from. This can be a local file, or a `http` or `ftp` connection. It can also be a character string with the file name or URI.
`format`	Character constant giving the file format. Right now `edgelist`, `pajek`, `ncol`, `lgl`, `graphml`, `dimacs`, `graphdb`, `gml` and `dl` are supported, the default is `edgelist`. As of igraph 0.4 this argument is case insensitive.
`...`	Additional arguments, see below.

Details

The read_graph function may have additional arguments depending on the file format (the format argument). See the details separately for each file format, below.

Value

A graph object.

Edge list format

This format is a simple text file with numeric vertex ids defining the edges. There is no need to have newline characters between the edges, a simple space will also do.

Additional arguments:

n: The number of vertices in the graph. If it is smaller than or equal to the largest integer in the file, then it is ignored; so it is safe to set it to zero (the default).
directed: Logical scalar, whether to create a directed graph. The default value is TRUE.

Author(s)

Gabor Csardi csardi.gabor@gmail.com