Waldir Leoncio Waldir Leoncio - 3 months ago 15
R Question

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?

Answer

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

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