Here is how to

If you don’t need help with either of these, then carry on.

Get to the starting line

Here’s how I would start the homework on making an R package. Basically you want to get the fiddliest moving parts working early and then keep it that way. In this case, I assume that means obtaining the foofactors package I have left for you to extend and making sure you can develop your own copy and push it back up to GitHub.

Option #1: Obtain foofactorsas a ZIP archive

Option #2: Fork foofactors and get your copy the Git way

Now you are ready to start modifying the package. Keep checking, committing, and pushing often.

Install your peer’s package

If you barrel ahead and install your peer’s foofactors package for review, it will likely overwrite the installation of your own foofactors package. Note: only your installed package is at risk. The source of your foofactors package lives on safely on your computer and on GitHub. And you could re-install from either source.

If you want to be more careful, here are two approaches to take more control of the situation.

Option A. Install peer’s work to different library

In this option we install the peer’s version of foofactors to a non-default library, leaving the installation of your own version intact.

First, restart your R session. Specifically, we don’t want your foofactors package to be loaded before we start this. To confirm this is true, enter search() and make sure you don’t see foofactors listed in the result.

Step 1. Create a temporary library

This is nothing more than creating a new directory on your computer. It’s where you’ll install and load your peer’s package from. Then we’ll delete it. I’m putting in my all purpose temp directory, but you can pick another location.

    tmp_lib <- "~/tmp/tmp_lib"
    dir.create(tmp_lib)

Navigate to this directory in some file browser or shell and confirm the directory exists.

Step 2. Install foofactors from your peer

Install your peer’s foofactors package from GitHub into your temporary library. Below, devtools::with_lib() prepends your usual list of libraries with tmp_lib. Don’t worry about the deprecation warning on with_lib(). I’m also opting to build your peer’s vignettes, which may cause some suggested packages to be installed. Load your peer’s package from tmp_lib and confirm you’re using the right version via maintainer().

    library(devtools)
    with_lib(tmp_lib,
             install_github("rebjoh/foofactors",
                            build_vignettes = TRUE))
    library(foofactors, lib.loc = tmp_lib)
    maintainer("foofactors")

Use the peer’s package and submit your review.

Step 3. Remove peer’s work after peer-review

Delete your temporary library any way you want. Restart your R session to clean out your loaded packages and rest assured that plain ol’ library(foofactors) will now load your version. Use maintainer() to check if you are worried. Here’s an R command to get rid of the temporary library.

    unlink(tmp_lib, recursive = TRUE)

Option B. Overwrite and re-install

In this option you temporarily overwrite your installed version of foofactors with the version of your peer. This means that during the peer review you will not be able to load and run your version of foofactors.

Step 1. Backup

Let’s make extra sure your foofactors source package is safely stored locally and on GitHub.

  • Is your package in working order, with everything saved and committed and pushed to GitHub? Do it now!
  • Launch RStudio in the Project corresponding to your foofactors package.

  • De-install foofactors and confirm it’s truly gone from your library:

    remove.packages("foofactors")
## Restart R session
library("foofactors")
## Error in library("foofactors") : there is no package called ‘foofactors’
  • Re-install foofactors and confirm it’s back in your library. Use RStudio’s “Build & Reload” then call fbind(), get help ?fbind, browse the vignette, etc.
  • De-install foofactors again (see above).

  • Re-install foofactors from GitHub this time.

    library(devtools)
install_github("YOURGITHUBUSERNAME/foofactors",
               build_vignettes = TRUE)
library("foofactors")

    Revisit spot checks from above that foofactors is back and in working order.

If everything works as expected, you can feel good that your package source is safely stored locally and on GitHub.

Step 2. Install foofactors from your peer

Now that you know that you can re-install your version of foofactors, it’s time to let your peer’s version of foofactors take over.

  • Install your peer’s foofactors, load it, check maintainer:

    library(devtools)
install_github("YOURPEER/foofactors", build_vignettes = TRUE) 
library(foofactors)
maintainer("foofactors")
## USE IT

  • Review peer’s version of foofactors.

Step 3. Re-install your version

Once you are done with the peer review, restore your own version of foofactors.

  • To install from your local source, launch RStudio in your foofactors Project and do “Build and Reload”.

  • Or install from GitHub

    devtools::install_github("YOURGITHUBUSERNAME/foofactors")

  • Either way, verify your version is now installed:

    maintainer("foofactors")
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