read.graph {igraph} | R Documentation |
The read.graph
function is able to read graphs in
various representations from a file, or from a http
connection. Currently some simple formats are supported.
read.graph(file, format = "edgelist", ...)
file |
The connection to read from. This can be a local file, or
a http or ftp URI. |
format |
Character constant giving the file format. Right now
edgelist , ncol and lgl are supported, the
default is edgelist . |
... |
Additional arguments, see below. |
The read.graph
function may have additional arguments depending
on the file format (the format
argument).
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.
There are no additional arguments for this format.
The resulting graph is always undirected. LGL cannot deal with files which contain multiple or loop edges, this is however not checked here, as a igraph is happy with these.
Additional arguments:
lgl
format is used by the Large Graph Layout
visualization software
(http://bioinformatics.icmb.utexas.edu/lgl), it can describe
undirected optionally weighted graphs. From the LGL manual:
“The second format is the LGL file format (.lgl file
suffix). This is yet another graph file format that tries to be
as stingy as possible with space, yet keeping the edge file in a
human readable (not binary) format. The format itself is like
the following:
# vertex1name vertex2name [optionalWeight] vertex3name [optionalWeight]Here, the first vertex of an edge is preceded with a pound sign '#'. Then each vertex that shares an edge with that vertex is listed one per line on subsequent lines.”
LGL cannot handle loop and multiple edges or directed graphs, but in a igraph it is not an error to have multiple and loop edges.
Additional arguments:
Other additional arguments will be used as graph attributes.
A graph object.
Gabor Csardi csardi@rmki.kfki.hu