Home > Custom Function > A shortcut function for install.packages() and library()

A shortcut function for install.packages() and library()

I enjoy trying difference kind of R packages. Since I have more than 1 computers (1 at home, 1 at office and a laptop)
it is troublesome to check whether I have installed some new packages for each computer. Therefore i wrote a function to load and install packages at once. If the package does not exist, then the it will be downloaded from CRAN and be loaded it.

packages<-function(x, repos="http://cran.r-project.org", ...){
   x <- deparse(substitute(x))
   if (!require(x,character.only=TRUE)){
      install.packages(pkgs=x, repos=repos, ...)
      require(x,character.only=TRUE)
   }
}
packages(Hmisc)

ThanksĀ richierocks for the suggestion of using deparse(substitute(x)) in the code.

richierocks’s

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Categories: Custom Function
  1. September 12, 2011 at 16:28

    Nice idea to combine install.packages and require. Couple of things about your code though.

    The standard way of retrieving the name of a variable in the parent environment is

    deparse(substitute(x))

    as.character does odd things for more complicated variable names. Compare

    f1 <- function(x) as.character(match.call()[[2]])
    f2 <- function(x) deparse(substitute(x))

    x <- 1:3
    f1(x)
    f2(x)
    f1(1:3)
    f2(1:3)

    Secondly, install.packages takes many arguments that it would be useful to be able to set. Use the ellipsis argument to achieve this.

    packages <- function(x, …){
    if(!is.character(x)) x <- deparse(substitute(x))
    if (!require(x, character.only = TRUE)){
    install.packages(x, …)
    require(x, character.only = TRUE)
    }
    }

  2. September 12, 2011 at 16:39

    Thanks for information!! Can I put your updated code into the main text of my post?

  3. eoecontributor
    September 14, 2011 at 09:37

    Have you tested that code? You can’t both test whether or not x is a character and use substitute – try running packages(mgcv).

    • September 14, 2011 at 13:48

      Good spot. No I hadn’t tested it.

      The problem is that when you pass a package name in unquoted, is.character gets confused and claims that the variable you passed in doesn’t exist.

      A slightly nasty workaround that I have checked.

      packages <- function(x, …){
      xname <- deparse(substitute(x))
      if(grepl('"', xname)) #input was a character vector anyway
      {
      xname <- x
      }
      if (!require(xname, character.only = TRUE)){
      install.packages(xname, …)
      require(xname, character.only = TRUE)
      }
      }
      packages(mgcv)
      packages("mgcv")

      The alternative if adding an argument that the user provides to say whether or not the first input was a character string or not. (This is what library does.)

  4. September 14, 2011 at 13:16

    Updated. Thank you!

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