Introduction to tidyverse

1 The tidyverse Style Guide

canyoureadthissentence?

Good coding style is like correct punctuation: you can manage without it, but it makes things easier to read.

The most important thing about the tidyverse style guide is that it provides consistency, making code easier to write because you need to make fewer decisions.

Tip
NoteFile Names

Avoid special characters in file names — stick with numbers, letters, -, and _.

# Good
fit_models.R
utility_functions.R

# Bad
fit models.R
foo.r
stuff.r
lab1.r
  • Leave spaces before and after operators (e.g. <-, =).
  • Put a space after a comma, not before.
  • Object names should be all lowercase, with words separated by an underscore.
#---------Spacing ------------
# Good
age <- c(6, 9, 15)
# Bad
age <- c(6,9,15)

# Good
data.frame(age_kid = age)
# Bad
data.frame(Age_kid=age)

#---------Object name ------------
# Good
day_one <- 1
day_1 <- 1
# Bad
DayOne <- 1
first_day_of_the_month <- 1

#---------Parentheses ------------
# Good
mean(x, na.rm = TRUE)
# Bad
mean (x, na.rm = TRUE)
mean( x, na.rm = TRUE )


#---------Function------------
# Good
function(x) {}

# Bad
function (x) {}
function(x){}

2 The Pipe Operator

What is the average of 4, 8, 16 — approximately?

Breaking the problem down:

  1. What is the average of 4, 8, 16 approximately?
  2. What is the average of 4, 8, 16 approximately?
  3. What is the average of 4, 8, 16 approximately?
NoteSolution 1: Functions within Functions
Code 
c(4, 8, 16)
[1]  4  8 16
Code 
mean(c(4, 8, 16))
[1] 9.333333
Code 
round(mean(c(4, 8, 16)))
[1] 9

Problem: Things get messy and harder to read as operations become more complex.

Code 
numbers <- c(4, 8, 16)
numbers
[1]  4  8 16
Code 
avg_number <- mean(numbers)
avg_number
[1] 9.333333
Code 
round(avg_number)
[1] 9

Problem: We end up with too many objects cluttering the Environment.

First, load the tidyverse:

Code 
# install.packages("tidyverse")
library(tidyverse)

The pipe |> passes the output of one function as the first argument of the next.

Keyboard shortcut: Ctrl/Cmd + Shift + M

Code 
c(4, 8, 16) |>
  mean() |>
  round()
[1] 9

Read this as: Combine 4, 8, and 16, then take the mean, then round the result.

This is equivalent to the composite function \[f \circ g \circ h(x)\], or round(mean(c(4, 8, 16))) — but much easier to read.

Generalized form

h(x) |>
  g() |>
  f()

Our example

Code 
c(4, 8, 16) |>
  mean() |>
  round()

3 Practice: The Pipe Operator

3.1 Exercise 1: Top 3 Scores

A class got these quiz scores: 72, 88, 95, 61, 79, 100, 83. Use the pipe to find the top 3 scores, from highest to lowest.

Hint: try sort(), rev(), and head().

Code 
c(72, 88, 95, 61, 79, 100, 83) |>
  sort() |>
  rev() |>
  head(3)
[1] 100  95  88

3.2 Exercise 2: How Many Words?

Count the number of words in the sentence "To be or not to be that is the question".

Hint: try strsplit(), unlist(), and length().

Code 
"To be or not to be that is the question" |>
  strsplit(split = " ") |>
  unlist() |>
  length()
[1] 10