Interact with the user to choose the package repositories to be used.
Logical. If true, use a graphical list: on Windows or
macOS GUI use a list box, and on a Unix-alike if tcltk and an X
server are available, use Tk widget. Otherwise use a text
A character vector of additional URLs: it is often helpful to use a named vector.
The default list of known repositories is stored in the file ‘R_HOME/etc/repositories’. That file can be edited for a site, or a user can have a personal copy in the file pointed to by the environment variable R_REPOSITORIES, or if this is unset or does not exist, in ‘HOME/.R/repositories’, which will take precedence.
A Bioconductor mirror can be selected by setting
options("BioC_mirror"), e.g. via
chooseBioCmirror — the default value is
The items that are preselected are those that are currently in
options("repos") plus those marked as default in the
list of known repositories.
The list of repositories offered depends on the setting of option
"pkgType" as some repositories only offer a subset of types
(e.g., only source packages or not macOS binary packages).
Further, for binary packages some repositories (notably R-Forge) only
offer packages for the current or recent versions of R.
"both" is equivalent to
Repository CRAN is treated specially: the value is taken from
the current setting of
getOption("repos") if this has an
"CRAN": this ensures mirror selection is sticky.
This function requires the R session to be interactive unless
ind is supplied.
This function is invoked mainly for its side effect of updating
options("repos"). It returns (invisibly) the previous
repos options setting (as a
list with component
NULL if no changes were applied.
This does not set the list of repositories at startup: to do
options(repos =) in a start up file (see help topic
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