Make new dependency checks happy

[hofnerb]

To make the new dependency checks on CRAN happy go along the following recipe (as suggested by Kurt Hornik).

1.) Copy the functions listed after Undefined global functions or variables: in the output from R CMD check in a variable txt:

txt <- "abline axis box hcl lines matlines matplot plot points polygon rgb"

2.) With the function

imports_for_undefined_globals <- function(txt, lst, selective = TRUE) {
    if(!missing(txt))
        lst <- scan(what = character(), text = txt, quiet = TRUE)
    nms <- lapply(lst, find)
    ind <- sapply(nms, length) > 0L
    imp <- split(lst[ind], substring(unlist(nms[ind]), 9L))
    if(selective) {
        sprintf("importFrom(%s)",
                vapply(Map(c, names(imp), imp),
                       function(e)
                           paste0("\"", e, "\"", collapse = ", "),
                       ""))
    } else {
        sprintf("import(\"%s\")", names(imp))
    }
}

one can obtain the imports via

writeLines(imports_for_undefined_globals(txt))

3.) Copy and paste the output to NAMESPACE.
4.) Add the packages to Imports in DESCRIPTION.