ex01_leave-it-in-the-data-frame.md

Leave your data in that big, beautiful data frame

Jenny Bryan 2018-04-02

Don’t create odd little excerpts and copies of your data.

Code style that results from (I speculate) minimizing the number of key presses.

## :(
sl <- iris[51:100,1]
pw <- iris[51:100,4]
plot(sl ~ pw)

This clutters the workspace with “loose parts”, sl and pw. Very soon, you are likely to forget what they are, which Species of iris they represent, and what the relationship between them is.

Leave the data in situ and reveal intent in your code

More verbose code conveys intent. Eliminating the Magic Numbers makes the code less likely to be, or become, wrong.

Here’s one way to do same in a tidyverse style:

library(tidyverse)

ggplot(
  filter(iris, Species == "versicolor"),
  aes(x = Petal.Width, y = Sepal.Length)
) + geom_point()

Another tidyverse approach, this time using the pipe operator, %>%

iris %>%
  filter(Species == "versicolor") %>%
  ggplot(aes(x = Petal.Width, y = Sepal.Length)) + ## <--- NOTE the `+` sign!!
  geom_point()

A base solution that still follows the principles of

• leave the data in data frame
• convey intent

plot(
  Sepal.Length ~ Petal.Width,
  data = subset(iris, subset = Species == "versicolor")
)