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diff --git a/Rguide.xml b/Rguide.xml deleted file mode 100644 index ef87872..0000000 --- a/Rguide.xml +++ /dev/null @@ -1,447 +0,0 @@ -<?xml version="1.0"?> -<html xmlns="http://www.w3.org/1999/xhtml"> - <head> - <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> - <link rel="stylesheet" type="text/css" href="styleguide.css"/> - <title>Google's R Style Guide</title> - </head> - - <body> - - <h1>Google's R Style Guide</h1> - - <p> - R is a high-level programming language used primarily for - statistical computing and graphics. The goal of the R - Programming Style Guide is to make our R code easier to read, - share, and verify. The rules below were designed in - collaboration with the entire R user community at Google. - - </p> - - - - - - - <h2>Summary: R Style Rules</h2> - - <ol> - <li><a href="#filenames">File Names</a>: end in <code>.R</code></li> - <li><a href="#identifiers">Identifiers</a>: <code>variable.name</code> - (or <code>variableName</code>), - <code>FunctionName</code>, <code>kConstantName</code></li> - <li><a href="#linelength">Line Length</a>: maximum 80 characters</li> - <li><a href="#indentation">Indentation</a>: two spaces, no tabs</li> - <li><a href="#spacing">Spacing</a></li> - <li><a href="#curlybraces">Curly Braces</a>: first on same line, last on - own line</li> - <li><a href="#else">else</a>: Surround else with braces </li> - <li><a href="#assignment">Assignment</a>: use <code><-</code>, not - <code>=</code></li> - <li><a href="#semicolons">Semicolons</a>: don't use them</li> - <li><a href="#generallayout"> General Layout and Ordering</a></li> - <li><a href="#comments"> Commenting Guidelines</a>: all comments begin - with <code>#</code> followed by a space; inline comments need two - spaces before the <code>#</code></li> - <li><a href="#functiondefinition">Function Definitions and Calls</a></li> - <li><a href="#functiondocumentation"> Function Documentation</a></li> - <li><a href="#examplefunction"> Example Function</a></li> - <li><a href="#todo"> TODO Style</a>: <code>TODO(username)</code></li> - </ol> - - <h2>Summary: R Language Rules</h2> - <ol> - <li><a href="#attach"> <code>attach</code></a>: avoid using it</li> - <li><a href="#functionlanguage"> Functions</a>: - errors should be raised using <code>stop()</code></li> - <li><a href="#object"> Objects and Methods</a>: avoid S4 objects and - methods when possible; never mix S3 and S4 </li> - </ol> - - <h3>Notation and Naming</h3> - - <h4 id="filenames">File Names</h4> - <p> - File names should end in <code>.R</code> and, of course, be - meaningful. - <br/> GOOD: <code>predict_ad_revenue.R</code> - <br/> BAD: <code><span style="color:red">foo.R</span></code> - </p> - - <h4 id="identifiers">Identifiers</h4> - <p> - Don't use underscores ( <code>_</code> ) or hyphens - ( <code>-</code> ) in identifiers. - Identifiers should be named according to the following conventions. - The preferred form for variable names is all lower case - letters and words separated with dots - (<code>variable.name</code>), but <code>variableName</code> - is also accepted; - function names have initial capital letters and no dots - (<code>FunctionName</code>); - constants are named like functions but with an initial - <code>k</code>. - </p> - <ul> - <li><code>variable.name</code> is preferred, <code>variableName</code> is accepted - <br/> GOOD: <code>avg.clicks</code> - <br/> OK: <code>avgClicks</code> - <br/> BAD: <code><span style="color:red">avg_Clicks</span></code> - </li> - <li><code>FunctionName </code> - <br/> GOOD: <code>CalculateAvgClicks</code> - <br/> BAD: <code><span style="color:red">calculate_avg_clicks - </span></code>, - <code><span style="color:red">calculateAvgClicks</span></code> - <br/> Make function names verbs. - <br/><em>Exception: When creating a classed object, the function - name (constructor) and class should match (e.g., lm).</em></li> - <li><code>kConstantName </code></li> - </ul> - - - <h3>Syntax</h3> - - <h4 id="linelength">Line Length</h4> -<p> - The maximum line length is 80 characters. -</p> - - <h4 id="indentation">Indentation</h4> - <p> - When indenting your code, use two spaces. Never use tabs or mix - tabs and spaces. - <br/><em>Exception: When a line break occurs inside parentheses, - align the wrapped line with the first character inside the - parenthesis.</em> - </p> - - <h4 id="spacing">Spacing</h4> - <p> - Place spaces around all binary operators (<code>=</code>, - <code>+</code>, <code>-</code>, <code><-</code>, etc.). - <br/><em> Exception: Spaces around <code>=</code>'s are - optional when passing parameters in a function call.</em> - </p> - <p> - Do not place a space before a comma, but always place one after a - comma. - <br/><br/> GOOD: - </p> -<pre>tab.prior <- table(df[df$days.from.opt < 0, "campaign.id"]) -total <- sum(x[, 1]) -total <- sum(x[1, ])</pre> - <p> - BAD: - </p> -<pre><span style="color:red">tab.prior <- table(df[df$days.from.opt<0, "campaign.id"]) # Needs spaces around '<' -tab.prior <- table(df[df$days.from.opt < 0,"campaign.id"]) # Needs a space after the comma -tab.prior<- table(df[df$days.from.opt < 0, "campaign.id"]) # Needs a space before <- -tab.prior<-table(df[df$days.from.opt < 0, "campaign.id"]) # Needs spaces around <- -total <- sum(x[,1]) # Needs a space after the comma -total <- sum(x[ ,1]) # Needs a space after the comma, not before</span> -</pre> - <p> - Place a space before left parenthesis, except in a function call. - </p> - <p> - GOOD: - <br/><code>if (debug)</code> - </p> - <p> - BAD: - <br/><code><span style="color:red">if(debug)</span></code> - </p> - <p> - Extra spacing (i.e., more than one space in a row) is okay if it - improves alignment of equals signs or arrows (<code><-</code>). - </p> -<pre>plot(x = x.coord, - y = data.mat[, MakeColName(metric, ptiles[1], "roiOpt")], - ylim = ylim, - xlab = "dates", - ylab = metric, - main = (paste(metric, " for 3 samples ", sep = ""))) -</pre> - <p> - Do not place spaces around code in parentheses or square brackets. - <br/><em> Exception: Always place a space after a comma.</em> - </p> - <p> - GOOD:</p><pre>if (debug) -x[1, ]</pre> - <p> - BAD:</p><pre><span style="color:red">if ( debug ) # No spaces around debug -x[1,] # Needs a space after the comma </span></pre> - - <h4 id="curlybraces">Curly Braces</h4> - <p> - An opening curly brace should never go on its own line; a closing - curly brace should always go on its own line. You may omit curly - braces when a block consists of a single statement; however, you - must <em>consistently</em> either use or not use curly braces for - single statement blocks. - </p> - <pre> -if (is.null(ylim)) { - ylim <- c(0, 0.06) -}</pre> - <p> - xor (but not both) - </p> - <pre> -if (is.null(ylim)) - ylim <- c(0, 0.06)</pre> - <p> - Always begin the body of a block on a new line. - </p> - <p> - BAD: - <br/><code><span style="color:red"> if (is.null(ylim)) - ylim <- c(0, 0.06)</span></code> - <br/><code><span style="color:red"> if (is.null(ylim)) - {ylim <- c(0, 0.06)} </span></code> - </p> - - <h4 id="else">Surround else with braces</h4> - <p> - An <code>else</code> statement should always be surrounded on the - same line by curly braces.</p> - <pre> -if (condition) { - one or more lines -} else { - one or more lines -} -</pre> - <p> - BAD:<br/> - </p> - <pre style="color:red"> -if (condition) { - one or more lines -} -else { - one or more lines -} -</pre> - <p> - BAD:<br/> - </p> - <pre style="color:red"> -if (condition) - one line -else - one line -</pre> - - <h4 id="assignment">Assignment</h4> - <p> - Use <code><-</code>, not <code>=</code>, for assignment. - </p> - <p> - GOOD: - <br/><code> x <- 5 </code> - </p> - <p> - BAD: - <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> |