Load multiple packages at once

Question

Several permutations of your proposed functions do work -- but only if you specify the character.only argument to be TRUE. Quick example:

lapply(x, require, character.only = TRUE)

The CRAN package pacman that I maintain (authored with Dason Kurkiewicz) can accomplish this:

So the user could do:

## install.packages("pacman")
pacman::p_load(dplyr, psych, tm) 

and if the package is missing p_load will download it from CRAN or Bioconductor.

This should do the trick:

lapply(x, FUN = function(X) {
    do.call("require", list(X)) 
})

(The key bit is that the args argument in do.call(what, args) must be a list --- even if it only has a single element!)

For someone who wants to install and load packages simultaneously I came across this function from this link

# ipak function: install and load multiple R packages.
# check to see if packages are installed. Install them if they are not, then load them into the R session.

ipak <- function(pkg){
new.pkg <- pkg[!(pkg %in% installed.packages()[, "Package"])]
if (length(new.pkg)) 
    install.packages(new.pkg, dependencies = TRUE)
sapply(pkg, require, character.only = TRUE)
}

# usage
packages <- c("ggplot2", "plyr", "reshape2", "RColorBrewer", "scales", "grid")
ipak(packages)

An alternative option comes from the package easypackages. Once installed, you can load packages in the most intuitive way:

libraries("plyr", "psych", "tm")

The package also includes a function to install several packages:

packages("plyr", "psych", "tm")

Reference here.