Minimal R Version

MinimalRVersion.R

#!/usr/bin/env Rscript

#' Minimal R version
#'
#' Find the lowest accepted R version for a package and all of its dependencies
#'
#' @param package Name of CRAN package
#'
#' @return A \code{\link[base]{numeric_version}} with the lowest possible R
#' version to install \code{package} and all of its dependencies
#'
#' @export
#'
#' @examples
#' MinimalRVersion("Seurat")
#'
MinimalRVersion <- function(package) {
  db <- utils::available.packages()
  deps <- unlist(
    x = tools::package_dependencies(
      packages = package,
      db = db,
      recursive = TRUE
    ),
    use.names = FALSE
  )
  deps <- c(package, intersect(x = deps, y = rownames(x = db)))
  db <- db[deps, c('Depends', 'Imports', 'LinkingTo')]
  rversions <- apply(
    X = db,
    MARGIN = 1,
    FUN = function(row) {
      row <- trimws(x = unlist(
        x = strsplit(x = row, split = ','),
        use.names = FALSE
      ))
      row <- grep(pattern = '^R \\(', x = row, value = TRUE)
      if (!length(x = row)) {
        return(NULL)
      }
      version <- unlist(x = regmatches(
        x = row,
        m = regexec(pattern = '\\d+\\.\\d+\\.\\d+', text = row)
      ))
      if (!length(x = version)) {
        version <- NULL
      }
      return(version)
    }
  )
  rversions <- unlist(
    x = Filter(f = Negate(f = is.null), x = rversions),
    use.names = FALSE
  )
  rversions <- lapply(
    X = rversions,
    FUN = numeric_version
  )
  return(Reduce(f = max, x = rversions))
}