37  Bubble charts

This graph is largely complete and just needs final proof reading.


This graph requires:

✅ three numeric (continuous) variables

37.1 Description

Bubble graphs display relationships between three numeric (continuous) variables.

The position on the x and y axis illustrates the relationship between the first two variables, and the size of the point (i.e., the bubble) conveys the numeric value of the third.

37.2 Set up

PACKAGES:

Install packages.

show/hide 
install.packages("palmerpenguins")
library(palmerpenguins)
library(ggplot2)

DATA:

Artwork by allison horst

The penguins data.

show/hide 
penguins <- palmerpenguins::penguins
glimpse(penguins)
#> Rows: 344
#> Columns: 8
#> $ species           <fct> Adelie, Adelie, Adelie…
#> $ island            <fct> Torgersen, Torgersen, …
#> $ bill_length_mm    <dbl> 39.1, 39.5, 40.3, NA, …
#> $ bill_depth_mm     <dbl> 18.7, 17.4, 18.0, NA, …
#> $ flipper_length_mm <int> 181, 186, 195, NA, 193…
#> $ body_mass_g       <int> 3750, 3800, 3250, NA, …
#> $ sex               <fct> male, female, female, …
#> $ year              <int> 2007, 2007, 2007, 2007…

37.3 Grammar

CODE:

  • Create labels with labs()

  • Map bill_length_mm to x axis

  • Map flipper_length_mm to y axis

  • Map body_mass_g to size

  • Set alpha to 1/3

  • Add scale_size(), set the range to c(0.1, 10) and name to "Body Mass (g)"

  • Move the legend to the bottom of the graph with theme(legend.position = "bottom")

show/hide 
labs_bubble <- labs(
  title = "Bill Length vs. Flipper Length",
  x = "Bill Length (mm)", y = "Flipper length (mm)", 
  size = "Body Mass (g)")

ggp2_bubble <- penguins |> 
  ggplot(
    aes(x = bill_length_mm, y = flipper_length_mm)) + 
  geom_point(aes(size = body_mass_g), alpha = 1/3) + 
  scale_size(range = c(.1, 10), 
             name = "Body Mass (g)") + 
  theme(legend.position = "bottom")

ggp2_bubble + 
  labs_bubble

GRAPH: