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Replace external R style guide
Internally, we've moved to the Tidyverse Style Guide: style.tidyverse.org The new file for Rguide.md reflects this fact and notes where we differ.
This commit is contained in:
Michael Quinn
parent
9c6b371f41
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@ -39,7 +39,7 @@ The following Google style guides live outside of this project:
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[objc]: objcguide.md
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[objc]: objcguide.md
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[java]: https://google.github.io/styleguide/javaguide.html
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[java]: https://google.github.io/styleguide/javaguide.html
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[py]: https://google.github.io/styleguide/pyguide.html
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[py]: https://google.github.io/styleguide/pyguide.html
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[r]: https://google.github.io/styleguide/Rguide.xml
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[r]: https://google.github.io/styleguide/Rguide.md
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[sh]: https://google.github.io/styleguide/shell.xml
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[sh]: https://google.github.io/styleguide/shell.xml
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[htmlcss]: https://google.github.io/styleguide/htmlcssguide.html
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[htmlcss]: https://google.github.io/styleguide/htmlcssguide.html
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[js]: https://google.github.io/styleguide/jsguide.html
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[js]: https://google.github.io/styleguide/jsguide.html
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109
Rguide.md
Normal file
109
Rguide.md
Normal file
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@ -0,0 +1,109 @@
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# Google's R Style Guide
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R is a high-level programming language used primarily for statistical computing
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and graphics. The goal of the R Programming Style Guide is to make our R code
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easier to read, share, and verify.
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The Google R Style Guide is a fork of the
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[Tidyverse Style Guide](https://style.tidyverse.org/) by Hadley Wickham
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[license](https://creativecommons.org/licenses/by-sa/2.0/). Google modifications
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were developed in collaboration with the internal R user community. The rest of
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this document explains Google's primary differences with the Tidyverse guide,
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and why these differences exist.
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## Syntax
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### Naming conventions
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Google prefers identifying functions with `BigCamelCase` to clearly distinguish
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them from other objects.
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```
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# Good
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DoNothing <- function() {
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return(invisible(NULL))
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}
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```
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The names of private functions should begin with a dot. This helps communicate
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both the origin of the function and its intended use.
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```
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# Good
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.DoNothingPrivately <- function() {
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return(invisible(NULL))
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}
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```
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We previously recommended naming objects with `dot.case`. We're moving away from
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that, as it creates confusion with S3 methods.
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### Don't use attach()
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The possibilities for creating errors when using `attach()` are numerous.
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## Pipes
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### Right-hand assignment
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We do not support using right-hand assignment.
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```
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# Bad
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iris %>%
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dplyr::summarize(max_petal = max(Petal.Width)) -> results
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```
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This convention differs substantially from practices in other languages and
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makes it harder to see in code where an object is defined. E.g. searching for
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`foo <-` is easier than searching for `foo <-` and `-> foo` (possibly split over
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lines).
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### Use explicit returns
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Do not rely on R's implicit return feature. It is better to be clear about your
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intent to `return()` an object.
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```
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# Good
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AddValues <- function(x, y) {
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return(x + y)
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}
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# Bad
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AddValues <- function(x, y) {
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x + y
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}
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```
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### Qualifying namespaces
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Users should explicitly qualify namespaces for all external functions.
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```
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# Good
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purrr::map()
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```
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We discourage using the `@import` Roxygen tag to bring in all functions into a
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NAMESPACE. Google has a very big R codebase, and importing all functions creates
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too much risk for name collisions.
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While there is a small performance penalty for using `::`, it makes it easier to
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understand dependencies in your code. There are some exceptions to this rule.
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* Infix functions (`%name%`) always need to be imported.
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* Certain `rlang` pronouns, notably `.data`, need to be imported.
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* Functions from default R packages, including `datasets`, `utils`,
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`grDevices`, `graphics`, `stats` and `methods`. If needed, you can `@import`
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the full package.
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When importing functions, place the `@importFrom` tag in the Roxygen header
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above the function where the external dependency is used.
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## Documentation
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### Package-level documentation
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All packages should have a package documentation file, in a
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`packagename-package.R` file.
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447
Rguide.xml
447
Rguide.xml
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@ -1,447 +0,0 @@
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<?xml version="1.0"?>
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
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<link rel="stylesheet" type="text/css" href="styleguide.css"/>
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<title>Google's R Style Guide</title>
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</head>
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<body>
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<h1>Google's R Style Guide</h1>
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<p>
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R is a high-level programming language used primarily for
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statistical computing and graphics. The goal of the R
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Programming Style Guide is to make our R code easier to read,
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share, and verify. The rules below were designed in
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collaboration with the entire R user community at Google.
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</p>
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<h2>Summary: R Style Rules</h2>
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<ol>
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<li><a href="#filenames">File Names</a>: end in <code>.R</code></li>
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<li><a href="#identifiers">Identifiers</a>: <code>variable.name</code>
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(or <code>variableName</code>),
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<code>FunctionName</code>, <code>kConstantName</code></li>
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<li><a href="#linelength">Line Length</a>: maximum 80 characters</li>
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<li><a href="#indentation">Indentation</a>: two spaces, no tabs</li>
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<li><a href="#spacing">Spacing</a></li>
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<li><a href="#curlybraces">Curly Braces</a>: first on same line, last on
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own line</li>
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<li><a href="#else">else</a>: Surround else with braces </li>
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<li><a href="#assignment">Assignment</a>: use <code><-</code>, not
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<code>=</code></li>
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<li><a href="#semicolons">Semicolons</a>: don't use them</li>
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<li><a href="#generallayout"> General Layout and Ordering</a></li>
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<li><a href="#comments"> Commenting Guidelines</a>: all comments begin
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with <code>#</code> followed by a space; inline comments need two
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spaces before the <code>#</code></li>
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<li><a href="#functiondefinition">Function Definitions and Calls</a></li>
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<li><a href="#functiondocumentation"> Function Documentation</a></li>
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<li><a href="#examplefunction"> Example Function</a></li>
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<li><a href="#todo"> TODO Style</a>: <code>TODO(username)</code></li>
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</ol>
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<h2>Summary: R Language Rules</h2>
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<ol>
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<li><a href="#attach"> <code>attach</code></a>: avoid using it</li>
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<li><a href="#functionlanguage"> Functions</a>:
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errors should be raised using <code>stop()</code></li>
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<li><a href="#object"> Objects and Methods</a>: avoid S4 objects and
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methods when possible; never mix S3 and S4 </li>
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</ol>
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<h3>Notation and Naming</h3>
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<h4 id="filenames">File Names</h4>
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<p>
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File names should end in <code>.R</code> and, of course, be
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meaningful.
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<br/> GOOD: <code>predict_ad_revenue.R</code>
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<br/> BAD: <code><span style="color:red">foo.R</span></code>
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</p>
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<h4 id="identifiers">Identifiers</h4>
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<p>
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Don't use underscores ( <code>_</code> ) or hyphens
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( <code>-</code> ) in identifiers.
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Identifiers should be named according to the following conventions.
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The preferred form for variable names is all lower case
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letters and words separated with dots
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(<code>variable.name</code>), but <code>variableName</code>
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is also accepted;
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function names have initial capital letters and no dots
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(<code>FunctionName</code>);
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constants are named like functions but with an initial
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<code>k</code>.
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</p>
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<ul>
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<li><code>variable.name</code> is preferred, <code>variableName</code> is accepted
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<br/> GOOD: <code>avg.clicks</code>
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<br/> OK: <code>avgClicks</code>
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<br/> BAD: <code><span style="color:red">avg_Clicks</span></code>
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</li>
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<li><code>FunctionName </code>
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<br/> GOOD: <code>CalculateAvgClicks</code>
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<br/> BAD: <code><span style="color:red">calculate_avg_clicks
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</span></code>,
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<code><span style="color:red">calculateAvgClicks</span></code>
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<br/> Make function names verbs.
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<br/><em>Exception: When creating a classed object, the function
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name (constructor) and class should match (e.g., lm).</em></li>
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<li><code>kConstantName </code></li>
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</ul>
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<h3>Syntax</h3>
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<h4 id="linelength">Line Length</h4>
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<p>
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The maximum line length is 80 characters.
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</p>
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<h4 id="indentation">Indentation</h4>
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<p>
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When indenting your code, use two spaces. Never use tabs or mix
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tabs and spaces.
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<br/><em>Exception: When a line break occurs inside parentheses,
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align the wrapped line with the first character inside the
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parenthesis.</em>
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</p>
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<h4 id="spacing">Spacing</h4>
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<p>
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Place spaces around all binary operators (<code>=</code>,
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<code>+</code>, <code>-</code>, <code><-</code>, etc.).
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<br/><em> Exception: Spaces around <code>=</code>'s are
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optional when passing parameters in a function call.</em>
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</p>
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<p>
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Do not place a space before a comma, but always place one after a
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comma.
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<br/><br/> GOOD:
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</p>
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<pre>tab.prior <- table(df[df$days.from.opt < 0, "campaign.id"])
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total <- sum(x[, 1])
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total <- sum(x[1, ])</pre>
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<p>
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BAD:
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</p>
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<pre><span style="color:red">tab.prior <- table(df[df$days.from.opt<0, "campaign.id"]) # Needs spaces around '<'
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tab.prior <- table(df[df$days.from.opt < 0,"campaign.id"]) # Needs a space after the comma
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tab.prior<- table(df[df$days.from.opt < 0, "campaign.id"]) # Needs a space before <-
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tab.prior<-table(df[df$days.from.opt < 0, "campaign.id"]) # Needs spaces around <-
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total <- sum(x[,1]) # Needs a space after the comma
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total <- sum(x[ ,1]) # Needs a space after the comma, not before</span>
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</pre>
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<p>
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Place a space before left parenthesis, except in a function call.
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</p>
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<p>
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GOOD:
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<br/><code>if (debug)</code>
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</p>
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<p>
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BAD:
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<br/><code><span style="color:red">if(debug)</span></code>
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</p>
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<p>
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Extra spacing (i.e., more than one space in a row) is okay if it
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improves alignment of equals signs or arrows (<code><-</code>).
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</p>
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<pre>plot(x = x.coord,
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y = data.mat[, MakeColName(metric, ptiles[1], "roiOpt")],
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ylim = ylim,
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xlab = "dates",
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ylab = metric,
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main = (paste(metric, " for 3 samples ", sep = "")))
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</pre>
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<p>
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Do not place spaces around code in parentheses or square brackets.
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<br/><em> Exception: Always place a space after a comma.</em>
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</p>
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<p>
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GOOD:</p><pre>if (debug)
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x[1, ]</pre>
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<p>
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BAD:</p><pre><span style="color:red">if ( debug ) # No spaces around debug
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x[1,] # Needs a space after the comma </span></pre>
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<h4 id="curlybraces">Curly Braces</h4>
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<p>
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An opening curly brace should never go on its own line; a closing
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curly brace should always go on its own line. You may omit curly
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braces when a block consists of a single statement; however, you
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must <em>consistently</em> either use or not use curly braces for
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single statement blocks.
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</p>
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<pre>
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if (is.null(ylim)) {
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ylim <- c(0, 0.06)
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}</pre>
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<p>
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xor (but not both)
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</p>
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<pre>
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if (is.null(ylim))
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ylim <- c(0, 0.06)</pre>
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<p>
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Always begin the body of a block on a new line.
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</p>
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<p>
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BAD:
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<br/><code><span style="color:red"> if (is.null(ylim))
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ylim <- c(0, 0.06)</span></code>
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<br/><code><span style="color:red"> if (is.null(ylim))
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{ylim <- c(0, 0.06)} </span></code>
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</p>
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<h4 id="else">Surround else with braces</h4>
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<p>
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An <code>else</code> statement should always be surrounded on the
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same line by curly braces.</p>
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<pre>
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if (condition) {
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one or more lines
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} else {
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one or more lines
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}
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</pre>
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<p>
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BAD:<br/>
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</p>
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<pre style="color:red">
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||||||
if (condition) {
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one or more lines
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}
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else {
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||||||
one or more lines
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||||||
}
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||||||
</pre>
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<p>
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BAD:<br/>
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||||||
</p>
|
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||||||
<pre style="color:red">
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||||||
if (condition)
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one line
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else
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one line
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</pre>
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<h4 id="assignment">Assignment</h4>
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<p>
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|
||||||
Use <code><-</code>, not <code>=</code>, for assignment.
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||||||
</p>
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||||||
<p>
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GOOD:
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<br/><code> x <- 5 </code>
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||||||
</p>
|
|
||||||
<p>
|
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||||||
BAD:
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||||||
<br/><code><span style="color:red"> x = 5</span></code>
|
|
||||||
</p>
|
|
||||||
<h4 id="semicolons">Semicolons</h4>
|
|
||||||
<p>
|
|
||||||
Do not terminate your lines with semicolons or use semicolons to
|
|
||||||
put more than one command on the same line. (Semicolons are not
|
|
||||||
necessary, and are omitted for consistency with other Google style
|
|
||||||
guides.)
|
|
||||||
</p>
|
|
||||||
|
|
||||||
|
|
||||||
<h3> Organization </h3>
|
|
||||||
<h4 id="generallayout">General Layout and Ordering</h4>
|
|
||||||
<p>
|
|
||||||
If everyone uses the same general ordering, we'll be able to
|
|
||||||
read and understand each other's scripts faster and more easily.
|
|
||||||
</p>
|
|
||||||
<ol>
|
|
||||||
<li>Copyright statement comment </li>
|
|
||||||
<li>Author comment</li>
|
|
||||||
<li>File description comment, including purpose of
|
|
||||||
program, inputs, and outputs</li>
|
|
||||||
<li><code>source()</code> and <code>library()</code> statements</li>
|
|
||||||
<li>Function definitions</li>
|
|
||||||
<li>Executed statements, if applicable (e.g.,
|
|
||||||
<code> print</code>, <code>plot</code>)</li>
|
|
||||||
</ol>
|
|
||||||
<p>
|
|
||||||
Unit tests should go in a separate file named
|
|
||||||
<code>originalfilename_test.R</code>.
|
|
||||||
</p>
|
|
||||||
<h4 id="comments">Commenting Guidelines</h4>
|
|
||||||
<p>
|
|
||||||
Comment your code. Entire commented lines should begin with
|
|
||||||
<code>#</code> and one space.
|
|
||||||
</p>
|
|
||||||
<p>
|
|
||||||
Short comments can be placed after code preceded by two spaces,
|
|
||||||
<code>#</code>, and then one space.
|
|
||||||
</p>
|
|
||||||
<pre># Create histogram of frequency of campaigns by pct budget spent.
|
|
||||||
hist(df$pct.spent,
|
|
||||||
breaks = "scott", # method for choosing number of buckets
|
|
||||||
main = "Histogram: fraction budget spent by campaignid",
|
|
||||||
xlab = "Fraction of budget spent",
|
|
||||||
ylab = "Frequency (count of campaignids)")
|
|
||||||
</pre>
|
|
||||||
<h4 id="functiondefinition">Function Definitions and
|
|
||||||
Calls</h4>
|
|
||||||
<p>
|
|
||||||
Function definitions should first list arguments without default
|
|
||||||
values, followed by those with default values.
|
|
||||||
</p>
|
|
||||||
<p>
|
|
||||||
In both function definitions and function calls, multiple
|
|
||||||
arguments per line are allowed; line breaks are only allowed
|
|
||||||
between assignments.
|
|
||||||
<br/>GOOD:
|
|
||||||
</p>
|
|
||||||
<pre>PredictCTR <- function(query, property, num.days,
|
|
||||||
show.plot = TRUE)
|
|
||||||
</pre>
|
|
||||||
BAD:
|
|
||||||
<pre><span style="color:red">PredictCTR <- function(query, property, num.days, show.plot =
|
|
||||||
TRUE)
|
|
||||||
</span></pre>
|
|
||||||
<p> Ideally, unit tests should serve as sample function calls (for
|
|
||||||
shared library routines).
|
|
||||||
</p>
|
|
||||||
<h4 id="functiondocumentation">Function Documentation</h4>
|
|
||||||
<p> Functions should contain a comments section immediately below
|
|
||||||
the function definition line. These comments should consist of a
|
|
||||||
one-sentence description of the function; a list of the function's
|
|
||||||
arguments, denoted by <code>Args:</code>, with a description of
|
|
||||||
each (including the data type); and a description of the return
|
|
||||||
value, denoted by <code>Returns:</code>. The comments should be
|
|
||||||
descriptive enough that a caller can use the function without
|
|
||||||
reading any of the function's code.
|
|
||||||
</p>
|
|
||||||
|
|
||||||
<h4 id="examplefunction">Example Function</h4>
|
|
||||||
<pre>
|
|
||||||
CalculateSampleCovariance <- function(x, y, verbose = TRUE) {
|
|
||||||
# Computes the sample covariance between two vectors.
|
|
||||||
#
|
|
||||||
# Args:
|
|
||||||
# x: One of two vectors whose sample covariance is to be calculated.
|
|
||||||
# y: The other vector. x and y must have the same length, greater than one,
|
|
||||||
# with no missing values.
|
|
||||||
# verbose: If TRUE, prints sample covariance; if not, not. Default is TRUE.
|
|
||||||
#
|
|
||||||
# Returns:
|
|
||||||
# The sample covariance between x and y.
|
|
||||||
n <- length(x)
|
|
||||||
# Error handling
|
|
||||||
if (n <= 1 || n != length(y)) {
|
|
||||||
stop("Arguments x and y have different lengths: ",
|
|
||||||
length(x), " and ", length(y), ".")
|
|
||||||
}
|
|
||||||
if (TRUE %in% is.na(x) || TRUE %in% is.na(y)) {
|
|
||||||
stop(" Arguments x and y must not have missing values.")
|
|
||||||
}
|
|
||||||
covariance <- var(x, y)
|
|
||||||
if (verbose)
|
|
||||||
cat("Covariance = ", round(covariance, 4), ".\n", sep = "")
|
|
||||||
return(covariance)
|
|
||||||
}
|
|
||||||
</pre>
|
|
||||||
|
|
||||||
<h4 id="todo">TODO Style</h4>
|
|
||||||
|
|
||||||
<p>
|
|
||||||
Use a consistent style for TODOs throughout your code.
|
|
||||||
<br/><code>TODO(username): Explicit description of action to
|
|
||||||
be taken</code>
|
|
||||||
</p>
|
|
||||||
|
|
||||||
|
|
||||||
<h3> Language </h3>
|
|
||||||
|
|
||||||
<h4 id="attach">Attach</h4>
|
|
||||||
<p> The possibilities for creating errors when using
|
|
||||||
<code>attach</code> are numerous. Avoid it.</p>
|
|
||||||
<h4 id="functionlanguage">Functions</h4>
|
|
||||||
<p> Errors should be raised using <code>stop()</code>.</p>
|
|
||||||
<h4 id="object">Objects and Methods</h4>
|
|
||||||
<p> The S language has two object systems, S3 and S4, both of which
|
|
||||||
are available in R. S3 methods are more interactive and flexible,
|
|
||||||
whereas S4 methods are more formal and rigorous. (For an illustration
|
|
||||||
of the two systems, see Thomas Lumley's
|
|
||||||
"Programmer's Niche: A Simple
|
|
||||||
Class, in S3 and S4" in R News 4/1, 2004, pgs. 33 - 36:
|
|
||||||
<a href="https://cran.r-project.org/doc/Rnews/Rnews_2004-1.pdf">
|
|
||||||
https://cran.r-project.org/doc/Rnews/Rnews_2004-1.pdf</a>.)
|
|
||||||
</p>
|
|
||||||
<p>Use S3 objects and methods unless there is a strong reason to use
|
|
||||||
S4 objects or methods. A primary justification for an S4 object
|
|
||||||
would be to use objects directly in C++ code. A primary
|
|
||||||
justification for an S4 generic/method would be to dispatch on two
|
|
||||||
arguments.
|
|
||||||
</p>
|
|
||||||
<p>Avoid mixing S3 and S4: S4 methods ignore S3 inheritance and
|
|
||||||
vice-versa.
|
|
||||||
</p>
|
|
||||||
|
|
||||||
|
|
||||||
<h3>Exceptions</h3>
|
|
||||||
|
|
||||||
<p>
|
|
||||||
The coding conventions described above should be followed, unless
|
|
||||||
there is good reason to do otherwise. Exceptions include legacy
|
|
||||||
code and modifying third-party code.
|
|
||||||
</p>
|
|
||||||
|
|
||||||
|
|
||||||
<h3>Parting Words</h3>
|
|
||||||
|
|
||||||
<p>
|
|
||||||
Use common sense and BE CONSISTENT.
|
|
||||||
</p>
|
|
||||||
<p>
|
|
||||||
If you are editing code, take a few minutes to look at the code around
|
|
||||||
you and determine its style. If others use spaces around their
|
|
||||||
<code>if </code>
|
|
||||||
clauses, you should, too. If their comments have little boxes of stars
|
|
||||||
around them, make your comments have little boxes of stars around them,
|
|
||||||
too.
|
|
||||||
</p>
|
|
||||||
<p>
|
|
||||||
The point of having style guidelines is to have a common vocabulary of
|
|
||||||
coding so people can concentrate on <em>what</em> you are saying,
|
|
||||||
rather than on <em>how</em> you are saying it. We present global style
|
|
||||||
rules here so people
|
|
||||||
know the vocabulary. But local style is also important. If code you add
|
|
||||||
to a file looks drastically different from the existing code around it,
|
|
||||||
the discontinuity will throw readers out of their rhythm when they go to
|
|
||||||
read it. Try to avoid this.
|
|
||||||
</p>
|
|
||||||
|
|
||||||
<p>
|
|
||||||
OK, enough writing about writing code; the code itself is much more
|
|
||||||
interesting. Have fun!
|
|
||||||
</p>
|
|
||||||
|
|
||||||
|
|
||||||
<h3>References</h3>
|
|
||||||
|
|
||||||
<p>
|
|
||||||
<a href="http://www.maths.lth.se/help/R/RCC/">
|
|
||||||
http://www.maths.lth.se/help/R/RCC/</a> - R Coding Conventions
|
|
||||||
</p>
|
|
||||||
<p>
|
|
||||||
<a href="http://ess.r-project.org/">http://ess.r-project.org/</a> - For
|
|
||||||
emacs users. This runs R in your emacs and has an emacs mode.
|
|
||||||
</p>
|
|
||||||
|
|
||||||
</body>
|
|
||||||
|
|
||||||
</html>
|
|
||||||
Loading…
Reference in New Issue
Block a user