Commands > FASTA/Q files, Reads
Quality control for OTU sequences
Filter low-complexity sequences.
Input is a FASTA or FASTQ file. A reverse (R2) read file can be specified
using -reverse, in which case a read pair is discarded if the forward (R1)
and/or reverse (R2) read is found to be low-complexity. If -reverse is specified,
-output2 must be specified for the reverse read output file.
written in the same format (FASTA or FASTQ) as the input.
A sequence is discarded if it is >25% low-complexity. This threshold can be
changed with the max_lowc_pct option.
The -hitsout file contains the low-complexity sequences that were removed.
The -tabbedout file species an output file in tabbed text format which
reports the percentage of low complexity sequence found in each of the query
Multithreading is supported.
usearch -filter_lowc reads.fq -output filtered_reads.fq -tabbedout lowc.txt
usearch -filter_lowc reads_fwd.fq -reverse reads_rev.fq -output fil_fwd.fq