class: center, middle, inverse, title-slide # Coding style <br> 👗 ### Dr. Çetinkaya-Rundel --- layout: true <div class="my-footer"> <span> Dr. Mine Çetinkaya-Rundel - <a href="http://www2.stat.duke.edu/courses/Fall18/sta112.01/schedule" target="_blank">stat.duke.edu/courses/Fall18/sta112.01 </a> </span> </div> --- ## Announcements - Peer evaluations for your teammates due Friday (tomorrow!) evening - Look for an email from TEAMMATES after class, ping me/Eidan if you don't see it in your inbox by this afternoon - HW 05 due next Tuesday - MT 01 assigned next Thursday, due following Tuesday --- class: center, middle # Coding style --- ## Style guide >"Good coding style is like correct punctuation: you can manage without it, butitsuremakesthingseasiertoread." > >Hadley Wickham - Style guide for this course is based on the Tidyverse style guide: http://style.tidyverse.org/ - There's more to it than what we'll cover today, but we'll mention more as we introduce more functionality, and do a recap later in the semester --- ## File names and code chunk labels - Do not use spaces in file names and code chunk labels, use `-` or `_` to separate words - Use all lowercase letters ```r # Good ucb-admit.csv # Bad UCB Admit.csv ``` --- ## Object names - Use `_` to separate words in object names - Use informative but short object names - Do not reuse object names within an analysis ```r # Good acs_employed # Bad acs.employed acs2 acs_subset acs_subsetted_for_males ``` --- ## Spacing - Put a space before and after all infix operators (=, +, -, <-, etc.), and when naming arguments in function calls - Always put a space after a comma, and never before (just like in regular English) ```r # Good average <- mean(feet / 12 + inches, na.rm = TRUE) # Bad average<-mean(feet/12+inches,na.rm=TRUE) ``` --- ## ggplot2 - Always end a line with `+` - Always indent the next line ```r # Good ggplot(diamonds, mapping = aes(x = price)) + geom_histogram() # Bad ggplot(diamonds,mapping=aes(x=price))+geom_histogram() ``` --- ## dplyr - Always end a line with `%>%`, except for one-step pipes - Always indent the next line ```r # Good diamonds %>% filter(cut == "Fair") diamonds %>% filter(cut == "Fair") %>% summarise(mean_price = mean(price)) # Bad diamonds %>% filter(cut == "Fair") %>% summarise(mean_price = mean(price)) diamonds %>% filter(cut == "Fair") %>% summarise(mean_price = mean(price)) ``` --- ## ggplot2 + dplyr - Further indent ggplot2 code following a dplyr pipeline ```r # Good diamonds %>% filter(cut == "Fair") %>% ggplot(aes(x = carat, y = price)) + geom_point() + labs(title = "Price vs. carat for fair diamonds") # Bad diamonds %>% filter(cut == "Fair") %>% ggplot(aes(x = carat, y = price)) + geom_point() + labs(title = "Price vs. carat for fair diamonds") ``` --- ## Long lines - Limit your code to 80 characters per line. This fits comfortably on a printed page with a reasonably sized font - Tools `\(\rightarrow\)` Global options `\(\rightarrow\)` Display `\(\rightarrow\)` check Show margin - Take advantage of RStudio editor's auto formatting for indentation at line breaks --- ## Assignment - Use `<-` not `=` ```r # Good x <- 2 # Bad x = 2 ``` --- ## Quotes - Use `"`, not `'`, for quoting text - The only exception is when the text already contains double quotes and no single quotes ```r ggplot(diamonds, mapping = aes(x = price)) + geom_histogram() + # Good labs(title = "`Shine bright like a diamond`", # Good x = "Diamond prices", # Bad y = 'Frequency') ``` --- ## Commenting - Use comments sparingly, instead describe important findings and decisions in text - If you need comments to explain what your code is doing, consider rewriting your code to be clearer - Leave one space after `#` - Place comments above the code when possible ```r # Good x <- 2 x = 2#Bad ``` --- ## 📦 styler .pull-left[ - The goal of **styler** is to provide non-invasive pretty-printing of R code adhering to the **tidyverse** formatting rules - You can use the *Style selection* or *Style active file* addins to use the package functionality - But styler doesn't catch all deviations from the guidelines we outlined, make sure to do a thorough review of your code! ] .pull-right[ <!-- --> ] --- class: center, middle # Application exercise --- ## <i class="fas fa-laptop"></i> AE 07 - Coding style - Clone your assignment repo in RStudio Cloud (`ae-07-coding-style-TEAMNAME`), and open the R Markdown file. - Review the document and make any stylistic corrections needed.