Binary graph file format

[Alpar Juttner]

The .lgf format is nice, but the files become extremely large for big graphs.

In some cases it would be nice to have a version of GraphReader/GraphWriter using a much more condensed binary format while providing close to the same API and feature set.

[Balazs Dezso]

Replying to alpar:

The .lgf format is nice, but the files become extremely large for big graphs.

In some cases it would be nice to have a version of GraphReader/GraphWriter using a much more condensed binary format while providing close to the same API and feature set.

It would be good, but it is not a requisite. I think the zipped and gzipped text files could substitute the binary files. They can be used efficiently, and it do not have the problem of binary compatibility, byte orders, etc.

The compressed text files can be used through POSIX pipes, or with C++ libraries, for example ost::OZStream and ost::IZStream.

[Alpar Juttner]

It is also a possible approach that the standard graph reader will hande the binary format, as well. It can be an option for the writer, while the reader may automatically recognise whether the file is a binary or plain text LGF.

[Frantisek Csajka]

The attached patch [454f0c2a380c] contains implementation of the BLGF (Binary Lemon Graph Format) as well as its documentation. BLGF can be read and written using the existing GraphReader,GraphWriter , DigraphReader and DigraphWriter classes. It provides almost the same features as the LGF.

Note: Portability problem of real types (i.e. byte order) is still not solved.