Appendix B: Appendix: Coding Style Guidelines

B.1 Why Style Matters

Consistent code style makes your work:

Easier to read (for you and collaborators)
Easier to debug (clean structure reveals problems quickly)
Easier to maintain (future you will thank present you)

This appendix summarizes the tidyverse style guide based on R4DS Workflow: Style.

B.2 File Naming

Use lowercase, descriptive names, and hyphens (not spaces).
Good: data-cleaning.R, plot-analysis.R
Bad: Data Cleaning.R, final.R

B.3 Object Naming

Use snake_case for variable and function names.
Be descriptive, not cryptic.

# Good
daily_sales <- 100
calculate_mean <- function(x) mean(x)

# Bad
ds <- 100
cm <- function(x) mean(x)

B.4 Spaces and Indentation

Use two spaces for indentation.
Always put a space after commas and around operators.

# Good
y <- x + 1
filter(mpg, cyl == 4)

# Bad
y<-x+1
filter(mpg,cyl==4)

B.5 Long Lines

Keep lines under 80 characters.
Use line breaks for long function calls.

mpg |>
  filter(cyl == 4, hwy > 30) |>
  arrange(desc(hwy))

B.6 Function Formatting

Use consistent curly brace placement.

# Good
my_function <- function(x) {
  x + 1
}

# Bad
my_function <- function(x){
x+1}

B.7 Commenting Code

Write comments to explain why, not what.
Use # for inline comments.

# Calculate average highway mpg for 4-cylinder cars
avg_hwy <- mpg |>
  filter(cyl == 4) |>
  summarize(mean_hwy = mean(hwy))

B.8 Piping

Each step in a pipeline goes on a new line.
Use the pipe |> to connect transformations.

mpg |>
  filter(cyl == 4) |>
  group_by(manufacturer) |>
  summarize(mean_hwy = mean(hwy))

B.9 Tidyverse Style Summary

Use |> for pipelines, snake_case for names
Indent two spaces per level
Avoid deeply nested code — break into steps
Write clear, short, and well-commented code

B.10 In-Class Exercise

Take a messy R script (provided in class).
Reformat it to follow these style guidelines.
Compare before vs. after readability.

B.11 Conclusion

Good code style is not just aesthetic — it improves reproducibility and collaboration.
Follow these conventions for all homework and projects in this course.

--- title: "Appendix: Coding Style Guidelines" --- ## Why Style Matters Consistent code style makes your work: - **Easier to read** (for you and collaborators) - **Easier to debug** (clean structure reveals problems quickly) - **Easier to maintain** (future you will thank present you) This appendix summarizes the **tidyverse style guide** based on [R4DS Workflow: Style](https://r4ds.hadley.nz/workflow-style.html). ------------------------------------------------------------------------ ## File Naming - Use **lowercase**, **descriptive names**, and **hyphens** (not spaces). - Good: `data-cleaning.R`, `plot-analysis.R` - Bad: `Data Cleaning.R`, `final.R` ------------------------------------------------------------------------ ## Object Naming - Use **snake_case** for variable and function names. - Be descriptive, not cryptic. ```{r} # Good daily_sales <- 100 calculate_mean <- function(x) mean(x) # Bad ds <- 100 cm <- function(x) mean(x) ``` ------------------------------------------------------------------------ ## Spaces and Indentation - Use **two spaces** for indentation. - Always put a space **after commas** and **around operators**. ```{r, eval=FALSE} # Good y <- x + 1 filter(mpg, cyl == 4) # Bad y<-x+1 filter(mpg,cyl==4) ``` ------------------------------------------------------------------------ ## Long Lines - Keep lines **under 80 characters**. - Use line breaks for long function calls. ```{r, eval=FALSE} mpg |> filter(cyl == 4, hwy > 30) |> arrange(desc(hwy)) ``` ------------------------------------------------------------------------ ## Function Formatting - Use consistent curly brace placement. ```{r, eval=FALSE} # Good my_function <- function(x) { x + 1 } # Bad my_function <- function(x){ x+1} ``` ------------------------------------------------------------------------ ## Commenting Code - Write **comments** to explain why, not what. - Use `#` for inline comments. ```{r, eval=FALSE} # Calculate average highway mpg for 4-cylinder cars avg_hwy <- mpg |> filter(cyl == 4) |> summarize(mean_hwy = mean(hwy)) ``` ------------------------------------------------------------------------ ## Piping - Each step in a pipeline goes on a **new line**. - Use the pipe `|>` to connect transformations. ```{r, eval=FALSE} mpg |> filter(cyl == 4) |> group_by(manufacturer) |> summarize(mean_hwy = mean(hwy)) ``` ------------------------------------------------------------------------ ## Tidyverse Style Summary - Use **`|>`** for pipelines, **snake_case** for names - Indent **two spaces** per level - Avoid deeply nested code — break into steps - Write **clear, short, and well-commented** code ------------------------------------------------------------------------ ## In-Class Exercise 1. Take a messy R script (provided in class).\ 2. Reformat it to follow these style guidelines.\ 3. Compare before vs. after readability. ------------------------------------------------------------------------ ## Conclusion Good code style is not just aesthetic — it improves **reproducibility** and **collaboration**.\ Follow these conventions for all homework and projects in this course.