get_taxa_unique: Get a unique vector of the observed taxa at a particular taxonomic rank
Description
This is a simple accessor function to make it more convenient to determine
the different taxa present for a particular taxonomic rank
in a given phyloseq-class object.
(Optional). Character. The taxonomic rank to use. Must select
from the set indicated by get_taxa_unique. Default is
to take the first column of the taxonomyTable component.
errorIfNULL
(Optional). Logical. Should the accessor stop with
an error if the slot is empty (NULL)? Default TRUE.
Value
Character vector. Unique vector of the observed taxa
at a particular taxonomic rank