The Graphical Fragment Assembly (GFA) described under is a proposed format which allows to describe the product of sequence assembly and is implemented in the RGFA class defined in the rgfa gem.

RGFATools is an extension to the RGFA library, which allow to perform further operations. Thereby additional conventions are required, with respect to the GFA specification, which are compatible with it.

The methods defined here allow, e.g., to randomly orient a segment which has the same connections on both sides, to compute copy numbers and multiply or delete segments according to them, to distribute the links of copies after multipling a segment, or to eliminate edges in the graph which are incompatible with an hamiltonian path.

Custom optional fields are defined, such as "cn" for the copy number of a segment, "or" for the original segment(s) of a duplicated or merged segment, "mp" for the starting position of original segments in a merged segment, "rp" for the position of possible inversions due to arbitrary orientation of some segments by the program.

Furthermore a convention for the naming of the segments is introduced, which gives a special meaning to the characters "_^()".

This gem is depends on the "rgfa" gem. Please install the rgfa gem first (

The API documentation is available as pdf under or in HTML format (


Giorgio Gonnella, Stefan Kurtz, "RGFA: powerful and convenient handling of assembly graphs" (2016)

The manuscript describing the library has been accepted for presentation at the German Conference on Bioinformatics 2016. The PeerJ preprint will be linked here, as soon as available.