???? R Coding Style Guide

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Language is a tool that allows human beings to interact and communicate with each other. The clearer we express ourselves, the better the idea is transferred from our mind to the other. The same applies to programming languages: concise, clear and consistent codes are easier to read and edit. It is especially important, if you have collaborators, which depend on your code. However, even if you don’t, keep in mind that at some point in time, you might come back to your code, for example, to fix an error. And if you did not follow consistently your coding style, reviewing your code can take much longer, than expected. In this context, taking care of your audience means to make your code as readable as possible.

Good coding style is like using correct punctuation. You can manage without it, but it sure makes things easier to read. Hadley Wickham

There is no such thing as a “correct” coding style, as there is no such thing as the best color. At the end of the day, coding style is a set of developers’ preferences. If you are coding alone, sticking to your coding style and being consistent is more than enough. The story is a bit different if you are working in a team: it is crucial to agree on a convention beforehand and make sure that everyone follows it.

Even though there is no official style guide, R is mature and steady enough to have an “unofficial” convention. In this post, you will learn these “unofficial” rules, their deviations, and most common styles.


Naming files

The convention actually depends on whether you develop a file for a package, or as a part of data analysis process. There are, however, common rules:

  • File names should use .R extension.

      # Good
      # Bad 
  • File names should be meaningful.

      # Good 
      # Bad
  • File names should not contain / and spaces. Instead, a dash (-) or underscore (_) should be used.

      # Good 
      # Bad
      fit regression.R
  • If the file is a part of data analysis, then it makes sense to follow the following recommendations:

  • Use meaningful verbs for file names.

      # Good 
      # Bad
  • If files should be run in a particular order, then use ascending names.

  • If the file is used in a package, then slightly different rules should be folowed:

    Naming variables

    Naming functions

    Many points of naming variables are similar for naming functions:

    Naming S4 classes

    Class names should be nouns in CamelCase with initial capital case letter.


    Line length

    The maximum length of lines is limited to 80 characters (thanks to IBM Punch Card).

    It is possible to display the margin in RStudio Source editor:


    Curly braces


    ALWAYS indent your code!

    Try a little exercise: paste the following code in your RStudio source editor, select it, and hit Command+I:

    for(i in 1:10) {
    if(i %% 2 == 0)
    print(paste(i, "is even"))

    New line


    Other recommendations

    If you have read until this moment, you deserve a treat. There is a magic key combination Command+Shift+A that reformats selected code: add spaces and indents it. Do not use it excessively though!


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