purrr: info

• Overview
• Cheatsheet
• Reading

Provides tools for working with functions and vectors

The purrr family of functions helps us replace for loops, making our code easier to read and more succint.

With purrr you can

• Iterate over a single input with map()
• Iterate over two inputs in parallel with map2()
• Iterate with multiple arguments with pmap()
• Iterate with multiple arguments and functions with invoke_map()
• Call a function for its side-effects with walk(), walk2(), and pwalk()

PDF: https://github.com/rstudio/cheatsheets/raw/main/purrr.pdf

{fig-alt=“R4DS book cover”}

R for Data Science: Ch 21 Iteration

Package documentation: https://purrr.tidyverse.org

purrr: exercise

• Time for a change?
• Goal
• Option 1
• Options 2 & 3
• Purrr?
• More palettes!

Ok, we love our earlier boxplot showing us body_mass_g by sex and colored by species…

…but let’s change up the colors to keep with our Antarctica theme!

I’m a big fan of the color palettes in the nord 📦

Let’s turn this plot…

…into this one!

Note: The color choices in this example are meant for demo purposes only. Be sure to consider the accessibility of your data viz, including color contrast between different elements.

You can choose colors using
the color hex codes

nord::nord_palettes$mountain_forms

[1] "#184860" "#486078" "#d8d8d8" "#484860" "#181830"

And assign them using the scale_fill_manual() function

penguins |>
  ggplot(aes(x = sex, y = body_mass_g)) +
  geom_boxplot(aes(fill = species)) +
  scale_fill_manual(
    values = c("#184860", 
               "#D8D8D8", 
               "#181830"))

You can also use the palette name, like mountain_forms, though the colors assigned may not align with what you want

penguins |>
  ggplot(aes(x = sex, y = body_mass_g)) +
  geom_boxplot(aes(fill = species)) +
  scale_fill_manual(
    values = nord::nord_palettes$mountain_forms
    )

And sometimes, color palette packages come with their own functions that assign colors, like scale_fill_nord()

penguins |>
  ggplot(aes(x = sex, y = body_mass_g)) +
  geom_boxplot(aes(fill = species)) +
  nord::scale_fill_nord(
    palette = "mountain_forms"
    )

The prismatic 📦 helps us see the colors that correspond to each color hex code (mostly), with the color() function

library(prismatic)

prismatic::color(
    nord::nord_palettes$mountain_forms
    )

purrr’s map() function can help us iterate color() over all palettes in a palette package like nord!

nord::nord_palettes |> 
    map(prismatic::color)

🎨 r-color-palettes repo from Emil Hvitfeldt

Like this Wes Anderson themed one! And many, many others 🤩