set xpos per species

Hi,

I am using the SankeyNetwork function of D3Network.

I was wondering, does NetworkD3 has a function to set the xpos for a set of nodes? I am using a bigger dataset with 61 links; all from 6 different species. I would like to set an xpos for the 6 species and see the gene flow horizontally, one species per xpos.

Ideally it would look something like this:
0 Pgla_V1_ctg0001 xpos=1
1 elephantNW_024704744.1 xpos=2
2 elephantNW_024704774.1 xpos=2
3 ssNC_052151.1 xpos=3
4 ssNC_052146.1 xpos=3
5 whiteNW_024470908.1 xpos=4

Kind regards!
Esther