documentation_rank.2
What rank(s) of taxa to compute biplot coordinates and
statistics for, or NULL to disable. E.g. "Phylum",
"Genus", ".otu", etc. An integer vector can also be
given, where 1 is the highest rank, 2 is the second
highest, -1 is the lowest rank, -2 is the second
lowest, and 0 is the OTU "rank". Run biom$ranks to
see all options for a given rbiom object. Default: 2.