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Last active Feb 25, 2019
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#' Simplified loading and installing of packages
#' This is a wrapper to \code{\link{require}} and \code{\link{install.packages}}.
#' Specifically, this will first try to load the package(s) and if not found
#' it will install then load the packages. Additionally, if the
#' \code{update=TRUE} parameter is specified it will check the currently
#' installed package version with what is available on CRAN (or mirror) and
#' install the newer version.
#' @param pkgs a character vector with the names of the packages to load.
#' @param install if TRUE (default), any packages not already installed will be.
#' @param update if TRUE, this function will install a newer version of the
#' package if available.
#' @param quiet if TRUE (default), package startup messages will be suppressed.
#' @param verbose if TRUE (default), diagnostic messages will be printed.
#' @param ... other parameters passed to \code{\link{require}},
#' \code{\link{install.packages}}, and
#' \code{\link{available.packages}}.
#' @return a data frame with four columns and rownames corresponding to the
#' packages to be loaded. The four columns are: loaded (logical
#' indicating whether the package was successfully loaded), installed
#' (logical indicating that the package was installed or updated),
#' loaded.version (the version string of the installed package), and
#' available.version (the version string of the package currently
#' available on CRAN). Note that this only reflects packages listed in
#' the \code{pkgs} parameter. Other packages may be loaded and/or
#' installed as necessary by \code{install.packages} and \code{require}.
#' If \code{verbose=FALSE} the data frame will be returned using
#' \code{\link{invisible}}.
#' @export
#' @example
#' \dontrun{
#' package(c('devtools','lattice','ggplot2','psych'))
#' }
package <- function(pkgs, install=TRUE, update=FALSE, quiet=TRUE, verbose=TRUE, ...) {
myrequire <- function(package, ...) {
result <- FALSE
if(quiet) {
suppressMessages(suppressWarnings(result <- require(package, ...)))
} else {
result <- suppressWarnings(require(package, ...))
mymessage <- function(msg) {
if(verbose) {
installedpkgs <- installed.packages()
availpkgs <- available.packages()[,c('Package','Version')]
if(nrow(availpkgs) == 0) {
warning(paste0('There appear to be no packages available from the ',
'repositories. Perhaps you are not connected to the ',
# It appears that hyphens (-) will be replaced with dots (.) in version
# numbers by the packageVersion function
availpkgs[,'Version'] <- gsub('-', '.', availpkgs[,'Version'])
results <- data.frame(loaded=rep(FALSE, length(pkgs)),
installed=rep(FALSE, length(pkgs)),
loaded.version=rep(as.character(NA), length(pkgs)),
available.version=rep(as.character(NA), length(pkgs)),
row.names(results) <- pkgs
for(i in pkgs) {
loadedPkgs <- search()
needInstall <- FALSE
if(i %in% row.names(installedpkgs)) {
v <- as.character(packageVersion(i))
if(i %in% row.names(availpkgs)) {
if(v != availpkgs[i,'Version']) {
if(!update) {
mymessage(paste0('A newer version of ', i,
' is available ', '(current=', v,
'; available=',
availpkgs[i,'Version'], ')'))
needInstall <- update
results[i,]$available.version <- availpkgs[i,'Version']
} else {
mymessage(paste0(i, ' is not available on the repositories.'))
} else {
if(i %in% row.names(availpkgs)) {
needInstall <- TRUE & install
results[i,]$available.version <- availpkgs[i,'Version']
} else {
warning(paste0(i, ' is not available on the repositories and ',
'is not installed locally'))
if(needInstall | !myrequire(i, character.only=TRUE)) {
install.packages(pkgs=i, quiet=quiet)
if(!myrequire(i, character.only=TRUE, ...)) {
warning(paste0('Error loading package: ', i))
} else {
results[i,]$installed <- TRUE
results[i,]$loaded <- TRUE
results[i,]$loaded.version <- as.character(packageVersion(i))
} else {
results[i,]$loaded <- TRUE
results[i,]$loaded.version <- as.character(packageVersion(i))
loadedPkgs2 <- search()
for(j in loadedPkgs2[!loadedPkgs2 %in% loadedPkgs]) {
try(detach(j, character.only=TRUE), silent=TRUE)
if(verbose) {
} else {

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@drbardach drbardach commented Jul 19, 2016

Hey, I am really enjoying your solution to the, "check if package is installed and install it if necessary" problem. Thanks for making it! But I am not able to install using devtools::source_gist(), no matter which format of the examples on the source_gist {devtools} documentation page I use. I keep getting Error in r_files[[which]] : invalid subscript type 'closure'. I haven't been able to find anything on Google for such an error, so I thought I would at least let you know to see if maybe that error indicates something wrong with how it is set up on Gist? Unlikely, I know, but thought it was worth bringing to your attention. In the meantime, copy-pasting it as a function that I source before analysis is working for me. Thanks again!

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