Conventions in the Book

One page holding every construct the book uses, so a theme or CSS change can be checked in one place, in both light and dark mode. This is a good reference page for how source code renders to the page.

You can learn more about features in the Quarto Guide.

Text

Body text, with bold, italic, inline code, a link to another page and an external link. Keyboard keys are written with <kbd>. Named keys take title case: Ctrl, Shift, Tab, Enter, Esc, Space, Up, Down. A letter key stays lowercase unless Shift is genuinely part of the shortcut, so that an uppercase letter never implies a Shift that isn’t there: Ctrl + c interrupts a command, while Ctrl + Shift + C opens the browser console. The same rule reads correctly for a program that treats case as meaning, such as n and N in less. Enough of them to wrap, so their boxes can be checked against each other on neighbouring lines: press Ctrl + c to stop a running command, Ctrl + d to close the shell, Tab to complete a path, Up and Down to walk back through your history, and Ctrl + r to search it.

A third-level heading

A fourth-level heading

An unordered list
with a second item
- and a nested item

An ordered list
with a second item

A blockquote.

Code

Every static listing carries a label saying where its contents belong, and the copy button says whether you are meant to take it: a listing you run or paste has one, a listing showing what the machine said back does not.

You are looking at	Fence	Label	Copy button
a command to run in the terminal	`bash`	automatic	yes
what the terminal printed back	`out`	automatic	no
code in a file, or typed at a console	`python`, `r`	`filename`	yes
the contents of a file	its own language, or `default`	`filename`	yes

bash and out are labelled by code-labels.lua, because those two labels never vary. Everything else says where it belongs with an explicit filename, because that is where a label earns its keep – penguins.py and pyproject.toml tell you something “Python” and “TOML” do not.

A command and what it printed, which is the pairing most of the book is made of. They are two listings, never one, so the command can be copied without dragging the output along with it:

Terminal

ls

Output

Applications    Pictures
Desktop         Documents       Movies
Downloads       Music

A listing that is a file, labelled with the file’s name:

penguins.py

from palmerpenguins import load_penguins

penguins = load_penguins()
print(penguins.head())

pyproject.toml

[project]
requires-python = ">=3.12"

A file with no language of its own. default is the fence for these: no highlighting, but still a copy button, because it is a listing you are meant to put somewhere:

.python-version

3.14

A listing typed at a console rather than saved to a file:

R Console

install.packages(c("xaringan", "revealjs"))

The remaining languages, which reach the page the same way:

# yaml listing, used for _quarto.yml and the GitHub Actions workflow
project:
  type: website

# markdown listing

sample_notebook.ipynb

{"cells": [{"cell_type": "markdown", "source": ["# A heading"]}]}

# a bare fence: no label, no highlighting, no copy button

A listing wider than the page, so the horizontal scrollbar can be checked. Real lines in the book reach about 150 characters:

Terminal

uv run --with 'numpy>=2.5.2' --with 'matplotlib>=3.11.1' python -c "import sys; print(sys.executable)" --directory ~/a/deeply/nested/project/path

Output wide enough to scroll, so the same can be checked on the quieter surface:

Output

cpython-3.14.7-macos-aarch64-none    /opt/homebrew/bin/python3.14 -> ../Cellar/python@3.14/3.14.7/bin/python3.14

A one-line command and a one-line output, the shortest the pairing gets:

Terminal

uv --version

Output

uv 0.12.6

Executed cells

A cell and its output:

# python code
a = 3
a**2

A cell showing its own fence, which is how the book explains chunk options:

```{python}
a + 1
```

An R cell and its output. The page is pinned to the knitr engine in the front matter, so the Python cells above run through reticulate, which picks up the uv venv from VIRTUAL_ENV when the book is rendered with uv run:

# r code
a <- 1:5
a^2

[1]  1  4  9 16 25

A cell that writes to stderr, which Quarto puts in an output block of its own. This one is R, because under knitr a Python warning arrives on stdout instead:

warning("a warning from a cell")

Warning: a warning from a cell

A cell whose output is a figure:

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [1, 4, 9])
plt.show()

Callouts

Note

A note!

Tip

A tip!

Warning

A warning!

Important

An important!

Caution

A caution!

Exercise

An exercise!

Activity

An activity!

Exercise

Another exercise!

Activity

Another activity!

Callouts hold listings too, and Quarto styles those differently from a listing out in the body:

Note

A note with a listing in it:

Terminal

ls -la

Quizzes

Quizzes are written in a quizdown fence and rendered by _extensions/quizdown, a fork of quizdown-js kept at UBC-MDS/quarto-quizdown-mds-ext. The fence never says which kind of question it holds – the type comes out of the shape of the list you write:

You write	You get
an unordered list whose items hold `::`	matching: drag a chip into a slot
an ordered list with no checkboxes	sequence: drag the lines into order
an unordered list of `- [ ]` and `- [x]`	multiple choice: tick every right answer
an ordered list of `1. [ ]` and `1. [x]`	single choice: tick the one right answer

Three optional pieces work in all four: a --- block of options above the question, a > blockquote under the heading, which becomes a hint behind a button, and a > blockquote indented under one answer, which becomes the feedback shown for that answer once the quiz is marked.

A quiz renders into a shadow root, which is a corner of the page that no stylesheet can reach into from outside. So the colours below do not come from styles.scss like everything else on this page – they come from quizdown-theme.html, which injects one stylesheet into each quiz. That is the thing all four of these are really here to check.

The book only uses the first two types so far. The other two are on this page anyway, because an unused construct is the one that breaks without anyone noticing.

Matching

Options, a hint and per-answer feedback, which the other three take the same way. An item with nothing on the left of its :: is a distractor: it joins the pool of chips but matches no prompt.

--- shuffle_answers: true --- ## Match each command to what it does > Every one of these appears in the first lecture. - `pwd` :: prints the directory you are in > Print Working Directory. - `ls` :: lists what is beside you - `cd` :: moves you somewhere else - :: prints your username

Sequence

## Put the steps of one trip around the shell's loop in order You type `ls -F` after the `$` prompt and press Enter. 1. The shell takes in the line you typed 2. The shell finds the `ls` program and runs it with the `-F` option 3. The program's output is written to the terminal 4. A fresh `$` prompt appears, waiting for the next command

Multiple choice

## Which of these are shells? - [x] `bash` - [x] `zsh` - [ ] `ls` > `ls` is a program you run *from* a shell. - [ ] JupyterLab

Single choice

## Which command prints the directory you are in? 1. [ ] `cd` 2. [x] `pwd` 3. [ ] `ls` 4. [ ] `whoami`

Tables

Command	Purpose	Example use
`pwd`	Print Working Directory	`pwd`
`ls`	LiSt contents	`ls Documents`
`cd`	Change Directory	`cd Desktop`

Math

Inline math, $y = mx + b$, and display math:

\[f'(a) = \lim_{x \to a} \frac{f(x) - f(a)}{x-a}\]

Figures

Tabsets

The contents of one tab, which is usually a listing:

Terminal

ssh-keygen -t ed25519 -C "you@example.com"

The contents of the other tab.