The read_graph function is able to read graphs in various
representations from a file, or from a http connection. Various formats
are supported.
read_graph(
file,
format = c("edgelist", "pajek", "ncol", "lgl", "graphml", "dimacs", "graphdb", "gml",
"dl"),
...
)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.
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.
A graph object.
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:
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).
Logical scalar, whether to create a directed graph. The
default value is TRUE.
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.