Data Visualization with R
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advice (4)
FAQs (6)
getting started (4)

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October 8, 2025 at 8:04 PM Week 6 FAQs
  • Am I telling R what to do with my code, or is it telling me what to do? Who’s in charge? Why isn’t it listening?!
  • Do I really need to make fancy custom themes for every plot? Aren’t theme_bw() or theme_gray() just fine?
  • I have numbers like 20000 and want them formatted with commas like 20,000. Can I do that automatically?
  • I tried using {gghalves} and geom_half_point() but I got an error?
  • My histogram bars are too wide / too narrow / not visible. How do I fix that?
  • Does it matter which order we put the different layers in?
FAQs
September 30, 2025 at 8:37 AM Week 5 FAQs
  • This is too much code—Tableau can do all this, so why can’t we use that?
  • Why should I use ggsave() instead of just rendering a Quarto document?
  • I made a bunch of changes to my plot with theme() but when I used ggsave(), none of them actually saved. Why?
  • Does the order of theme things matter? I made changes with theme() and then wiped them out with theme_minimal()?
  • If I want to use the same theme for all the plots in my document, do I need to reuse all that code all the time?
  • Why would we want to use rel(1.4) instead of actual numbers when sizing things?
  • Why can’t I change title text with theme()?
  • I’m using macOS and couldn’t render as PDF when using a custom font—how do I fix that?
  • In chapter 22, Wilke talks about tables—is there a way to make pretty tables with R?
  • Double encoding and excessive legends
  • Legends are cool, but I’ve read that directly labeling things can be better. Is there a way to label things without a legend?
  • Can we fill with a pattern instead of colors?
FAQs
September 22, 2025 at 4:40 PM Week 4 FAQs
  • I can’t remember everything I need to type / I can’t memorize all the code / I had to look stuff up on the internet / Why didn’t you cover this specific thing?
  • It seems weird that we can randomly jitter points to accurately reveal relationships?
  • I want my lollipop/bar chart to go sideways—how do I do that?
  • Why does R keep yelling at me with warnings and messages?
  • Why do I keep getting messages like summarise() has grouped output by 'BLAH' when using group_by() and summarize()?
  • When do we use summarize() vs. mutate() with group_by()?
  • How can I hide warnings and messages?
  • Why did we need to group a second time when calculating the proportions for the heatmap?
  • How can I add a line break to the text in my plot?
  • How can I control the dimensions of my figures?
FAQs
September 19, 2025 at 7:54 PM Week 3 FAQs
  • What’s the difference between the |> and %>% pipes?
  • Why do we sometimes combine code with + and sometimes with |>?
  • Why doesn’t group_by(species) work but group_by(Species) does?
  • Why does aes() sometimes appear in ggplot() and sometimes in geom_WHATEVER()?
  • Installing vs. using packages
  • Why are my axis labels all crowded and on top of each other? How do I fix that?
  • Why isn’t the example code using data = whatever and mapping = aes() in ggplot() anymore? Do we not have to use argument names?
  • What’s the difference between geom_bar() and geom_col()?
  • What’s the difference between read_csv() vs. read.csv()?
  • What’s the difference between facet_grid() and facet_wrap()?
  • Why do I sometimes see facet_wrap(vars(blah)) and sometimes facet_wrap(~ blah)?
  • What’s the difference between the fill and color aesthetics?
  • Why did we need to group and summarize before making the Lord of the Rings plots? I didn’t and the plot still worked
FAQs
September 9, 2025 at 11:03 AM Week 2 FAQs
  • Why do you use ✓s for grades?
  • Why does # mean both headings and code comments?
  • I will never do anything with graphic design—why did we have to learn these principles?
  • How does CRAP relate to other things like the Gestalt Principles?
  • Does something need to have all four elements to be well designed? Or can it have contrast and not alignment?
  • Are the CRAP principles hard-and-fast rules? Will following CRAP lead to the same final designs?
  • Does CRAP only work for single-page things like graphs and posters? Or does it work for reports and books?
  • I noticed Illustrator isn’t free for GSU students anymore. Are there other graphics editors?
  • Is there a way to check that my color palettes are accessible if I’m not using a premade one?
  • I wanted to try other fonts, but I can only see a few in Microsoft Word? Where can I find fonts to use?
FAQs
September 6, 2025 at 3:58 PM Copy, paste, and tweak
advice
September 6, 2025 at 2:58 PM Making cleaner, nicer Quarto documents
  • Render often
  • Check for broken code chunks
  • Check that your text looks okay
  • Don’t install packages in your document
  • Clean up warnings and messages
  • Global chunk options
  • Fancy document settings
  • Chunk names
advice
September 6, 2025 at 2:00 PM Week 1 tips and FAQs
  • What’s the difference between Source and Visual mode in the editor window?
  • What’s the difference between R Markdown and Quarto?
  • Why don’t I have options to render to PDF (or Word or HTML)?
  • Rendered document format for iCollege
  • What is this thing that we can render to?
  • How does group_by() work? Why did we have to group by island and not body_mass and island?
  • How do we know which type of graph to use for different types of data?
  • Do you have any tips for remembering all the different functions we’re learning? There are so many!
FAQs
August 25, 2025 at 3:14 PM How to ask for help
  • Don’t suffer in silence!
  • Use Discord in public
  • Help us help you
  • High resolution questions
  • Unanswered questions
  • Discord question etiquette
  • Calendly + Webex appointments
advice
August 25, 2025 at 3:12 PM First day of class!
getting started
August 21, 2025 at 2:44 PM Building community on Discord
  • Class community
  • Online community
advice
August 21, 2025 at 1:18 PM Announcements and updates
getting started
August 21, 2025 at 12:42 AM Important R stuff
getting started
August 20, 2025 at 1:08 PM Welcome to class!
getting started
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Content 2025 by Andrew Heiss
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