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 as.formula barplot boxplot citation coef coefficients
     complete.cases fivenum lm plot qnorm qt sd sessionInfo symnum vcov"

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