3.3 Radian

Q: There is no syntax highlighting in the R terminal. How to fix it?
A: Install Radian, an improved R console REPL interface that corrects many limitations of the official R terminal and supports many features such as syntax highlighting and auto-completion.

Q: How to install Radian?
A: In the terminal, run

$pipx install radian
  installed package radian 0.6.15, installed using Python 3.13.5
  These apps are now globally available
    - radian
⚠️  Note: '/Users/menghan/.local/bin' is not on your PATH environment variable. These apps will not be globally
    accessible until your PATH is updated. Run `pipx ensurepath` to automatically add it, or manually modify your PATH in
    your shell's config file (e.g. ~/.bashrc).
done! ✨ 🌟 ✨

$pipx ensurepath

/Users/menghan/.local/bin has been been added to PATH, but you need to open a new terminal or re-login for this PATH
    change to take effect. Alternatively, you can source your shell's config file with e.g. 'source ~/.bashrc'.

You will need to open a new terminal or re-login for the PATH changes to take effect. Alternatively, you can source your
shell's config file with e.g. 'source ~/.bashrc'.

N.B. If you have zsh as your shell, you need to run source ~/.zshrc instead of source ~/.bashrc.

To find where radian is installed, you can run:

which radian
/Users/menghan/.local/bin/radian

This is the path to the radian executable.

After adding Radian to your PATH, you can invoke it in the terminal by simply typing radian.

$radian
R version 4.3.1 (2023-06-16) -- "Beagle Scouts"
Platform: aarch64-apple-darwin20 (64-bit)

r$>

Then, in VS Code, you will need to set Radian as the default R terminal. You can also configure other settings for R.

{
  "r.rterm.mac": "/Users/menghan/.local/bin/radian",
  "r.bracketedPaste": true,
  "r.sessionWatcher": true,
}

• r.rterm.mac: Path to the Radian executable.

• r.bracketedPaste: Enables bracketed paste mode, which allows pasting code without executing it immediately. This is useful if you want to paste multiple lines of code into the console at once.

• r.sessionWatcher: Enables session watcher to monitor the R session. Specifically,

  • Show value of session symbols on hover
  • Show plot output on update and plot history
  • Show htmlwidgets, documentation and shiny apps in WebView

• r.alwaysUseActiveTerminal: always send code to active terminal rather than vscode-R; helps me to start an R session which is terminated when VSCode exits.

• r.plot.useHttpgd: Use the httpgd package for viewing plots in a VS Code window or in the browser.

See Extension Settings for a full list of settings of vscode-R that can be set in VSCode’s settings.json file.

3.3.1 Configuration

radian can be customized by specifying the below options in various locations:

• $HOME/.config/radian/profile
• .radian_profile in the working directory

Example of a radian profile

# either  `"emacs"` (default) or `"vi"`.
options(radian.editing_mode = "vi")

# enable various emacs bindings in vi insert mode
options(radian.emacs_bindings_in_vi_insert_mode = TRUE)

# show vi mode state when radian.editing_mode is `vi`
options(radian.show_vi_mode_prompt = TRUE)
options(radian.vi_mode_prompt = "\033[0;34m[{}]\033[0m ")

# custom key bindings
options(
    radian.escape_key_map = list(
        list(key = "-", value = " <- "),
    ),
    radian.ctrl_key_map = list(
        list(key = "p", value = " %>% ")
    )
)

• Insert pipe operator %>% by pressing Ctrl + P

• Insert assignment operator <- by pressing Esc + -

  But this does not work when Vim is enabled as it interferes with Vim’s normal mode.

VI support by radian:

• options(radian.editing_mode = "vi"): set the default editing mode to vi.

• options(radian.show_vi_mode_prompt = TRUE): This option will show the current vi mode in the prompt when using radian in vi mode. The prompt will be colored blue and will display the current mode.

  • [ins]: insert mode
  • [nav]: normal mode

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Q: How to restart Radian?
A: Run rstudioapi::restartSession() in the R terminal.

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