Visualization of read quality profiles plot - thin heatmap

[mmladinic]

Hi,

I am running

plotQualityProfile(fnFs[1:1])

on R version 4.5.2,
BiocManager version 1.30.27,
dada2 version 1.38.0

and I get plot as shown in image below.
Why is my heat map thin?

[benjjneb]

Your sequencing data has binned quality scores -- only four unique quality scores are present in the fastq files, thus only four quality scores show up as non-zero on this heat map.