确定所有包依赖项的最小R版本

我是一个软件包开发人员,想要说明在DESCRIPTION文件中使用我的软件包所需的最低R版本.

available.packages解析包的描述,但结果不是(容易)机器可读的查找递归依赖,因为Imports和Depends字段是逗号分隔文本,有时包含包有版本要求.

解决方案描述于：
Listing R Package Dependencies Without Installing Packages不是递归解决方案.如果嵌套依赖性需要R> 3.3,我想了解它.

至少,我希望看到给定CRAN包的R和导入,链接和依赖包的最低版本.更好的是列出设置最小R或包版本的包或包.

通过消除具有更高版本要求的依赖关系,我可以为更多人提供他们无法解决的系统旧R版本：一些仍然在R 2.x.

min_r_version <- function(package="ggplot2", exclude_main_pkg=TRUE) {

  purrr::walk(c("tools", "purrr", "devtools", "stringi", "tidyr", "dplyr"), 
              require, character.only=TRUE)

  deps <- package_dependencies(package, recursive=TRUE)

  if (exclude_main_pkg) {
    pkgs <- deps[[1]]
  } else {
    pkgs <- c(package, deps[[1]])
  }

  available.packages() %>% 
    as_data_frame() %>% 
    filter(Package %in% pkgs) %>% 
    select(Depends)  %>% 
    unlist() -> pkg_list

  # if main pkg only relied on core R packages (i.e. pkgs that aren't in CRAN) and we 
  # excluded the pkg itself from the min version calculation, this is an edge case we need
  # to handle.

  if (length(pkg_list) == 0) return("Unspecified")

  stri_split_regex(pkg_list, "[,]") %>%
    unlist() %>%
    trimws() %>%
    stri_match_all_regex(c("^R$|^R \\(.*\\)$")) %>%
    unlist() %>%
    discard(is.na(.)) %>%
    unique() %>%
    stri_replace_all_regex("[R >=\\(\\)]", "") %>%
    data_frame(vs=.) %>%
    separate(vs, c("a", "b", "c"), fill="right") %>%
    mutate(c=ifelse(is.na(c), 0, c)) %>%
    arrange(a, b, c) %>%
    tail(1) %>%
    unite(min, a:c, sep=".") -> vs

  return(vs$min)

}

# did we handle the edge cases well enought?
base <- c("base", "compiler", "datasets", "grDevices", "graphics", "grid", "methods", "parallel", "profile", "splines", "stats", "stats4", "tcltk", "tools", "translations")
(base_reqs <- purrr::map_chr(base, min_r_version))
##  [1] "Unspecified" "Unspecified" "Unspecified" "Unspecified" "Unspecified"
##  [6] "Unspecified" "Unspecified" "Unspecified" "Unspecified" "Unspecified"
## [11] "Unspecified" "Unspecified" "Unspecified" "Unspecified" "Unspecified"

# a few of the "core" contributed pkgs rely on a pkg or two outside of base
# but many only rely on base packages, to this is another gd edge case to
# text for.
contrib <- c("KernSmooth", "MASS", "Matrix", "boot", "class", "cluster", "codetools", "foreign", "lattice", "mgcv", "nlme", "nnet", "rpart", "spatial", "survival")
contrib_reqs <- purrr::map_chr(contrib, min_r_version)
##  [1] "Unspecified" "Unspecified" "3.0.0"       "Unspecified" "3.1.0"      
##  [6] "Unspecified" "Unspecified" "Unspecified" "Unspecified" "3.0.2"      
## [11] "3.0.0"       "Unspecified" "Unspecified" "Unspecified" "3.0.1"      

# See what the min version of R shld be for some of my pkgs
min_r_version("ggalt") # I claim R (>= 3.0.0) in DESCRIPTION
## [1] "3.1.2"

min_r_version("curlconverter") # I claim R (>= 3.0.0) in DESCRIPTION
## [1] "3.1.2"

min_r_version("iptools") # I claim R (>= 3.0.0) in DESCRIPTION
## [1] "3.0.0"