radian: a modern console for R

June 18, 2019
By

(This article was first published on From the Bottom of the Heap - R, and kindly contributed to R-bloggers)

Whenever I’m developing R code or writing data wrangling or analysis scripts for research projects that I work on I use Emacs and its add-on package Emacs Speaks Statistics (ESS). I’ve done so for nigh on a couple of decades now, ever since I switched full time to running Linux as my daily OS. For years this has served me well, though I wouldn’t call myself an Emacs expert; not even close! With a bit of help from some R Core coding standards document I got indentation working how I like it, I learned to contort my fingers in weird and wonderful ways to execute a small set of useful shortcuts, and I even committed some of those shortcuts to memory. More recently, however, my go-to methods for configuring Emacs+ESS were failing; indentation was all over the shop, the smart _ stopped working or didn’t work as it had for over a decade, syntax highlighting of R-related files, like .Rmd was hit and miss, and polymode was just a mystery to me. Configuring Emacs+ESS was becoming much more of a chore, and rather unhelpfully, my problems coincided with my having less and less time to devote to tinkering with my computer setups. Also, fiddling with this stuff just wasn’t fun any more. So, in a fit of pique following one to many reconfiguration sessions of Emacs+ESS, I went in search of some greener grass. During that search I came across radian, a neat, attractive, simple console for working with R.

Written by Randy Lai, radian is a cross-platform console for R that provides code completion, syntax highlighting, etc in a neat little package that runs in a shell or terminal, such as Bash. I’m someone who fires up multiple terminals every day to run some bit of R code, to show a student how to do something, to quickly check on argument names or such like, or prepare an answer to a question on stackoverflow or crossvalidated. Running R in a terminal after using an IDE/environment like Emacs+ESS or RStudio is an exercise in time travel; all those little helpful editing tools the IDE provides are missing and you’re coding like it was the 1980s all over again. radian changes all that.

radian is a Python application so to run it you’ll need a python stack installed. You’ll also need a relatively recent version of R (≥ 3.4.0). Using pip, the python package installer, installing radian is straightforward. Python v3 is recommended and on Fedora this mean I had to install using

pip-3 install --user radian

The –user flag does an user install, which sets the installation location to be inside your home directory. Once installed, you can start radian by simply typing the application name and hitting enter

radian

A nice configuration tip included in the radian README.md is to alias the radian command to r, so that running R runs the standard R console, while running r starts radian. On Fedora, you configure this alias in your ~/.bashrc file

alias r="radian"

Having started radian you’ll see something like this

radian at start-up running in a bash shell on Fedora
radian at start-up running in a bash shell on Fedora

radian starts up with a simple statement of the R version running in radian and the platform (OS) it’s running on; so is it just a less-verbose version of the standard R console? The radian prompt hints at the greater capabilities however.

Code completion is a nice addition; yes, you have some form of code completion in the standard R console but in radian we have a more RStudio or Emacs+ESS-like experience with a drop-down menu for object, function, argument, and filename completion. To activate this you start typing, hit Tab and the relevant completions pops up. Hit Tab again or press the down cursor and you can scroll through the potential completions.

Code completion in radian
Code completion in radian

We also get nice syntax highlighting of R code using the colour schemes from pygments:

Syntax highlighting in radian using the monokai theme
Syntax highlighting in radian using the monokai theme

And, if you’re copying & pasting code into the terminal or piping code in from a editor with an embedded terminal (that’s running radian) then you also get rather handy multiline editing. Pressing the up cursor will retrieve the previous set of commands pasted or piped into radian, and repeatedly pressin will scroll back through the history. If you want to edit a set of R calls, instead of pressing again, press to enter the chunk of code and then you can move around among the lines using the cursor keys, editing as you see fit. Hitting enter will run the entire chunk of code for you, edits and all:

Multiline editing a ggplot call in radian
Multiline editing a ggplot call in radian

You can configure aspects of the behaviour of radian via options() in your .Rprofile. The options I’m currently using on the computer used for the screenshots in this post are:

options(radian.auto_indentation = FALSE)
options(radian.color_scheme = "monokai")

but on my laptop I’m currently using

# auto match brackets and quotes
options(radian.auto_match = TRUE)

# auto indentation for new line and curly braces
options(radian.auto_indentation = TRUE)
options(radian.tab_size = 4)

# timeout in seconds to cancel completion if it takes too long
# set it to 0 to disable it
options(radian.completion_timeout = 0.05)

# insert new line between prompts
options(radian.insert_new_line = FALSE)

The last option is something I’m not sure about yet; as you can see in the screenshots, there’s a new line between the prompts, which makes it super easy to read the R code you’ve entered, but with the font I’m currently using (Iosevka) things look a bit too spread out. Setting radian.insert_new_line = FALSE, as I have it on the laptop results in more standard behaviour but it can feel a little cramped. I’ll probably play with both options and see which I like best after a few more weeks of use.

You can also define shortcuts. This is useful for entering the assignment operator <-, which I have bound to Alt + - using

options(radian.escape_key_map = list(
          list(key = "-", value = " <- ")
        ))

where I’ve added spaces around the operator to mimic how the smart underscore works in Emacs+ESS.

I’m really liking using radian for my throw-away R sessions that I typically do in a terminal. The only issue I’ve noticed is that it is a little slow to print tibbles, and clearly it’s not going to replace my current IDE — that’s not what it is designed for. That said, radian can be run inside any app that can run a terminal and I’ve had this running inside VS Code for example, which was nice.

If you have any comments on radian or other R consoles, let me know what you think below; if you’ve used radian I’m especially interested in your experience with it.

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