If have to generate legacy blastx output from Blast XML output (why do people still require this!!!?). The legacy output has a block starting with
Score E
Sequences producing significant alignments: (bits) Value N
dbseq_1 399 e-109 2
dbseq_2 389 e-106 3
The parameters N is documented as follows:
Ungapped alignments and results from blastx and tblastn will have an additional column ('N'), displaying the number of different segment pairs used to produce the alignment, according to the Karlin-Altschul statistics.
I have no idea, how to get this value out of the Blast XML file. Can anybody help me? If not, this post is intended to clarify this issue for others in future.