write_adjlist#

write_adjlist(G, path, comments='#', delimiter=' ', encoding='utf-8')[source]#

Write graph G in single-line adjacency-list format to path.

Parameters:

GNetworkX graph
pathstring or file: Filename or file handle for data output. Filenames ending in .gz or .bz2 will be compressed.
commentsstring, optional: Marker for comment lines
delimiterstring, optional: Separator for node labels
encodingstring, optional: Text encoding.

See also

read_adjlist, generate_adjlist

Notes

The default delimiter=" " will result in unexpected results if node names contain whitespace characters. To avoid this problem, specify an alternate delimiter when spaces are valid in node names. NB: This option is not available for data that isn’t user-generated.

This format does not store graph, node, or edge data.

Examples

>>> from pathlib import Path
>>> import tempfile
>>> tmp_path = Path(tempfile.gettempdir())

>>> G = nx.path_graph(4)
>>> fpath = tmp_path / "path4.adjlist"
>>> nx.write_adjlist(G, fpath)

View the data as stored in file, ignoring header lines which start with the comment character (“#” by default):

>>> with open(fpath) as fh:
...     lines_from_file = fh.readlines()
>>> print("".join(l for l in lines_from_file if not l.startswith("#")))
0 1
1 2
2 3
3

The path can be a filehandle or a string with the name of the file. If a filehandle is provided, it has to be opened in ‘wb’ mode.

>>> with open(tmp_path / "path4.adjlist2", "wb") as fh:
...     nx.write_adjlist(G, fh)
>>> with open(tmp_path / "path4.adjlist2") as fh:
...     lines_from_file = fh.readlines()
>>> print("".join(l for l in lines_from_file if not l.startswith("#")))
0 1
1 2
2 3
3