A reference database in UDB format is required. The makeudb_utax command is used to create the database. See UTAX downloads page for available reference files. See How to train UTAX on user data if you want to use your own reference data.
Taxonomy predictions are written to the utaxout file. Predictions in the -utaxout file are written twice: once with confidence values and once after applying a confidence threshold, keeping only ranks with high enough confidence. The threshold is specified by the -utax_cutoff option (default 0.9).
The -rdpout option species an output file in the format used by the RDP Naive Bayesian Classifier stand-alone program. This is for compatibility with existing scripts designed for RDP (supported in usearch v8.1.1786 and later).
The -alnout option specifies a human-readable output file
showing the alignment to the top hit and identities with the nearest neighbors
at each rank (see example file here). This is useful
for manual review of predictions. Note that this option will cause the utax
command to execute more slowly as more calculations are needed to create the
alignments.
The -fastaout option specifies a FASTA file. Output sequences
are written with a tax= annotation in the labels specifying the taxonomy
prediction with confidences.
The strand option must be specified.
Multithreading is supported.
Example
usearch -utax reads.fastq -db 16s.udb -utaxout reads.utax -strand both
-alnout aln.txt