Scatterplots

Getting Started

First, be sure you have installed ggformula. Remember, you only need to install the package once on your machine.

Then, be sure to load the package ggformula. Remember, you need to do this with each new Quarto/RMarkdown document or R Session.

#| label: setup
library(ggformula) #for graphs

Data for Examples Show

As a reminder (see Overview of Data Visualization, we will be using the penguins data from the palmerpenguins package:

library(palmerpenguins)

Here is a snippet of the data:

Palmer Penguins
species	island	bill_length_mm	bill_depth_mm	flipper_length_mm	body_mass_g	sex	year
Chinstrap	Dream	46.0	18.9	195	4150	female	2007
Adelie	Torgersen	38.9	17.8	181	3625	female	2007
Chinstrap	Dream	53.5	19.9	205	4500	male	2008
Adelie	Dream	36.6	18.4	184	3475	female	2009
Adelie	Torgersen	39.5	17.4	186	3800	female	2007

Scatterplots

Basic Code

For two quantitative variables, x and y, here is the general structure for a scatterplot.

gf_point(y ~ x, data = mydata)

Run the code below to see an example using the quantitative variables bill_length_mm and bill_depth_mm from the penguins data. Then replace bill_length_mm with another quantitative variable from the penguins data or switch the order to see what happens.

#| label: scatterplot-one
gf_point(bill_length_mm ~ bill_depth_mm, 
         data = penguins)

Warnings in R

Notice the warning produced from running the code. This is just a warning that there were rows (penguins) ignored due to missing data for the variables visualized. A Warning is simply R communicating a decision it made without your consent. The code still works.

Adding a Regression Line