Mutational signatures data from COSMIC, the Catalogue Of Somatic Mutations In Cancer (https://cancer.sanger.ac.uk/signatures/). There are also some helper functions for handling COSMIC signatures.
Install cosmicsig from the master branch on GitHub:
if (!requireNamespace("remotes", quietly = TRUE)) {
install.packages("remotes")
}
remotes::install_github(repo = "Rozen-Lab/cosmicsig", ref = "master")
https://github.com/Rozen-Lab/cosmicsig/blob/master/cosmicsig_1.0.7.pdf