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One of the more tedious parts of working with R is maintaining my R library. To make my R scripts reproducible and sharable, I will install packages if they are not available. For example, the top of my R scripts tend to look something like this:

if(!require(devtools) | !require(ggplot2) | !require(psych) | !require(lme4) | !require(benchmark)) {
install.packages(c('devtools','ggplot2','psych','lme4','benchmark'))
}

This has worked fine for some time, but I felt there was a better approach. First, note that if any one package doesn’t load (usually because it is not installed), all the packages are installed. I could separate the if statement so there is one per package, but then I have even more lines in my R script. Instead, I have written a function that will load each package separately and install only those that are not present. And optionally will even update packages using the update parameter. For example, I can now replace the above with one call to package:

> package(c('devtools','ggplot2','psych','lme4','benchmark'))

The output is minimal by default (set quiet=FALSE to get all the messages printed by require and install.packages). Even though verbose=TRUE by default, the only messages it will print is to indicate that a newer version of a package is available or that the package is not available on the repositories. In place of output to the console, a data frame is returned with a summary of what packages have been loaded and/or installed along with the loaded and available versions. Here are the results from the command above:

A newer version of lme4 is available (current=1.0.5; available=1.0.6)

devtools    TRUE     FALSE          1.4.1             1.4.1
ggplot2     TRUE     FALSE        0.9.3.1           0.9.3.1
psych       TRUE     FALSE        1.4.2.3           1.4.2.3
lme4        TRUE     FALSE          1.0.5             1.0.6
benchmark   TRUE      TRUE          0.3.5             0.3.5

Note that if I had specified update=TRUE (it is FALSE by default) the lme4 package would have been automatically updated.

In summary, I have collapsed what usually takes several lines within my R scripts to just one line, or two if you need to source this function. However, I just source this function in my .Rprofile so that it is always available. The only potential downside is that this is not part of base R and requires anyone you share your R scripts with to also have this function available.

The sourse code is on Gist here: https://gist.github.com/jbryer/9112634
With devtools installed you can just source function using:

> source_gist(9112634)