How to use Code Sections

Code sections - are you using them right?
ADaM
Technical
Author

Edoardo Mancini

Published

July 14, 2023

Introduction

The admiral package embraces a modular style of programming, where blocks of code are pieced together in sequence to create an ADaM dataset. However, with the well-documented advantages of the modular approach comes the recognition that scripts will on average be longer. As such, astute programmers working in RStudio are constantly on the lookout for quick ways to effectively navigate their scripts. Enter code sections!

So, what are code sections and why are they useful?

Code Sections are separators for long R scripts or functions in RStudio. They can be set up by inserting a comment line followed by four or more dashes in between portions of code, like so:

# First code section ----

a <- 1

# Second code section ----

b <- 2

# Third code section ----

c <- 3

RStudio then recognizes the code sections automatically, and enables you to:

  • Collapse and expand them using the arrow displayed next to the line number, or with the handy shortcuts Alt+L/Shift+Alt+L on Windows or Cmd+Option+L/Cmd+Shift+Option+L on Mac.
  • Travel in between them using the navigator at the bottom of the code pane, or by pressing Shift+Alt+J on Windows or Cmd+Shift+Option+J on Mac.
  • View an outline of the file using the “Outline” button at the top right of the pane and/or the orange hashtag “Section Navigator” button at the bottom left of the pane.

Collapsed sections, outline view and the section navigator for the example above.

It is also possible to create subsections by using two hashtags at the start of a comment line:

# First code section ----
a <- 1

## A code subsection ----
b <- 2

# Second code section ----
c <- 3

Code subsections for the example above.

For a complete list of Code Sections shortcuts, and for further information, see here.

Code Sections on admiral

Within the admiral package, heavy use of code sections is made in scripts such as our template ADaM programs. This ensures that they are more traversable and also encourages good commenting practices throughout the program. Here is an example using the ADAE template program:

library(admiral)
use_ad_template("ADAE")

Once the user saves this template program and opens it in their local file system, a 100+ line file instantly becomes more tractable due to the code sections that have been inserted.

A screenshot of the code sections in the ADAE template script

Conclusion

Code sections are an easy way to navigate long scripts and foster good commenting practices. They are used extensively in the admiral package, but there is no reason that you cannot start using them yourself in your day-to-day R programming!

Last updated

2024-04-15 15:23:58.876129

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Citation

BibTeX citation:
@online{mancini2023,
  author = {Mancini, Edoardo},
  title = {How to Use {Code} {Sections}},
  date = {2023-07-14},
  url = {https://pharmaverse.github.io/blog/posts/2023-07-14_code_sections/code_sections.html},
  langid = {en}
}
For attribution, please cite this work as:
Mancini, Edoardo. 2023. “How to Use Code Sections.” July 14, 2023. https://pharmaverse.github.io/blog/posts/2023-07-14_code_sections/code_sections.html.