install_deps: Install package dependencies if needed.
In devtools: Tools to Make Developing R Packages Easier

install_deps() will install the user dependencies needed to run the package, install_dev_deps() will also install the development dependencies needed to test and build the package.

install_deps(pkg = ".", dependencies = NA,
  repos = getOption("repos"), type = getOption("pkgType"),
  upgrade = c("default", "ask", "always", "never"), quiet = FALSE,
  build = TRUE, build_opts = c("--no-resave-data", "--no-manual",
  " --no-build-vignettes"), ...)

install_dev_deps(pkg = ".", dependencies = TRUE,
  repos = getOption("repos"), type = getOption("pkgType"),
  upgrade = c("default", "ask", "always", "never"), quiet = FALSE,
  build = TRUE, build_opts = c("--no-resave-data", "--no-manual",
  " --no-build-vignettes"), ...)

`pkg`	The package to use, can be a file path to the package or a package object. See `as.package()` for more information.
`dependencies`	Which dependencies do you want to check? Can be a character vector (selecting from "Depends", "Imports", "LinkingTo", "Suggests", or "Enhances"), or a logical vector. `TRUE` is shorthand for "Depends", "Imports", "LinkingTo" and "Suggests". `NA` is shorthand for "Depends", "Imports" and "LinkingTo" and is the default. `FALSE` is shorthand for no dependencies (i.e. just check this package, not its dependencies).
`repos`	A character vector giving repositories to use.
`type`	Type of package to `update`.
`upgrade`	One of "default", "ask", "always", or "never". "default" respects the value of the `R_REMOTES_UPGRADE` environment variable if set, and falls back to "ask" if unset. "ask" prompts the user for which out of date packages to upgrade. For non-interactive sessions "ask" is equivalent to "always". `TRUE` and `FALSE` are also accepted and correspond to "always" and "never" respectively.
`quiet`	If `TRUE`, suppress output.
`build`	If `TRUE` build the package before installing.
`build_opts`	Options to pass to `R CMD build`, only used when `build`
`...`	additional arguments passed to `utils::install.packages()`.