R on Puhti and package installations

This tutorial is done on Puhti, which requires that:

You have a user account at CSC.

Your account belongs to a project that has access to the Puhti service.

💬 A pre-installed R environment is available on Puhti.

To check available module versions, run:
```
 module spider r-env
```
There are several ways to use R in r-env on Puhti:
- Interactive jobs on a compute node, using either the R console or RStudio
  💡 The easiest way to launch RStudio is to use the Puhti web interface at www.puhti.csc.fi
- Non-interactive batch jobs
- Interactively on the login node, using the R console (only for moving data, checking package availability, installing packages)
For example, to launch the R console in an interactive job, open a shell with sinteractive and then
```
module load r-env
start-r
```

💡 See the r-env documentation for further instructions on different ways to launch R on Puhti.

💬 It is also possible to install R packages yourself.

☝🏻 However, check first if what you need is already available in r-env. The module contains more than 1300 R packages! The easiest way to check if a package is available is trying to load it with the command library(packagename).

How to install an R package on Puhti

Note that your own package installations are:
- project specific
- R version specific
- located in the /projappl directory of your project

Create a folder for your R packages in /projappl (open a login node shell in the Puhti web interface or log in to Puhti with SSH):

cd /projappl/<project>  # replace <project> with your CSC project, e.g. project_2001234
mkdir project_rpackages_<rversion>

Start an R session:
1. Launch RStudio in the Puhti web interface
2. … or launch the R console in an interactive shell session:
```
sinteractive 
module load r-env
start-r
```
In R, add the folder you created above to the list of directories where R will look for packages:
```
.libPaths(c("/projappl/<project>/project_rpackages_<rversion>", .libPaths())) 
```
Assign libpath to point to this directory (not strictly necessary, but can make life easier):
```
libpath <- .libPaths()[1]
```
Install the package (again, defining lib = libpath to specify the installation location is not strictly necessary, but recommended):
```
install.packages("packagename", lib = libpath)
```
For example, you can try installing a package called beepr with:
```
install.packages("beepr", lib = libpath)
```
Finished! The R package is now ready to be loaded and used. Try loading beepr with library(beepr).

💡 The package location is defined only for the current R session! R has to be reminded of the location at the start of every R session or script where you want to use the project-specific package by running this command again:

.libPaths(c("/projappl/<project>/project_rpackages_<rversion>", .libPaths())) 

💡 Instead of installing a missing package for your own project, you can ask for a module-wide installation for all users by contacting CSC Service Desk.

More information

💡 Docs CSC: Read more about using R on Puhti in our r-env documentation.