Check for installed packages before running install.packages()

I have an R script that is shared with several users on different computers. One of its lines contains the install.packages("xtable") command.

The problem is that every time someone runs the script, R spends a great deal of time apparently reinstalling the package (it actually does take some time, since the real case has vector of several packages).

How can I make first check if the packages are installed and then only run install.packages() for the ones that are not?


  • try: require("xtable") or "xtable" %in% rownames(installed.packages())


    if(!require("xtable")) install.packages("xtable")