fastman: A fast algorithm for visualizing GWAS results using Manhattan and Q-Q plots
Visualisation of GWAS summary statistics, specifically P-values, as Manhattan plots are widespread in GWAS publications, and many popular software tools are available, such as the R package qqman. However, there is a substantial need for further development, such as handling datasets from non-model organisms. We provide a new R package, fastman, with major additional capabilities compared to currently available packages. For example, it handles datasets involving genomes from non-model organisms, even at a draft stage consisting of numerous contigs and scaffolds (shorter stretches of assembled DNA sequences) that have not been compiled into chromosomes. Non-numeric chromosome IDs are also supported. Additionally, our package has the capability of plotting other genetic scores, such as other GWAS statistics (e.g. regression betas or odds ratios), fixation index(FST), D-statistics, and various selection statistics, such as PBS. Importantly, negative or two-tailed values are supported in this package. In our package, we implement a heuristic algorithm that drastically reduces plotting time for huge datasets without losing visual precision, allowing for many different data types and missing data. We also provide substantial additional flexibility in highlighting and annotation. The package can produce plots directly from association outputs by PLINK. Alternatively, it can produce plots from any R data frame with custom columns and can handle large datasets to generate plots rapidly. It is available for public use at https://github.com/adhikari-statgen-lab/fastman.