Vector of the quality scores used by the FASTQ format

A vector of the characters used to indicate quality scores from 0 to 40 in the FASTQ format. These scores are related to the error probability \(p\) via \(Q = -10 \text{ log}_{10}(p)\), so a Q-score of 10 (represented by "+") means the error probability is 0.1, a Q-score of 20 ("5") means the error probability is 0.01, and a Q-score of 30 ("?") means the error probability is 0.001.

The character representations store Q-scores in one byte each by using ASCII encodings, where the Q-score for a character is its ASCII code minus 33 (e.g. A has an ASCII code of 65 and represents a Q-score of 32).

This vector contains the characters in order but starting with a score of 0, meaning the character at index \(n\) represents a Q-score of \(n-1\) e.g. the first character ("!") represents a score of 0; the eleventh character ("+") represents a score of 10.

The full set of possible score representations, in order and presented as a single string, is !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHI.

Generation code is available at data-raw/fastq_quality_scores.R

Usage

fastq_quality_scores

Format

fastq_quality_scores

A character vector of length 41

fastq_quality_scores

The vector c("!", '"', "#", "$", "%", "&", "'", "(", ")", "*", "+", ",", "-", ".", "/", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", ":", ";", "<", "=", ">", "?", "@", "A", "B", "C", "D", "E", "F", "G", "H", "I")