Report statistics on ASCII characters used to represent quality scores in a FASTQ file. Useful for guessing FASTQ options for a file of unknown format.
Statistics are written as progress messages to standard error output (stderr). The output can be saved to a file by specifying a log file with the -log option.
The output indicates the range of ASCII values found in the quality scores, and reports a guess at the appropriate FASTQ options. Here is a typical output for a FASTQ file in Sanger format:
Qmin 66, QMax 104, Range 39
Also reported is the frequency of each nucleotide and the range of ASCII Q score(s) corresponding to any undetermined bases (Ns), e.g.:
N Freq MaxRun
reads.fastq -log chars.log