Quarto Pseudocode Extension

---

🇺🇸 README | 🇨🇳 中文说明

A Quarto extension to render pseudocode for HTML and PDF document. It's based on pseudocode.js for HTML document, algorithm and algpseudocodex package for PDF document.

Installing

quarto add leovan/quarto-pseudocode

This will install the extension under the _extensions subdirectory. If you're using version control, you will want to check in this directory.

Using

Adding Extension

Add this in the header of your document, or in the _quarto.yml file:

filters:
  - pseudocode

Pseudocode Block

Add the pseudocode in a code block marked with pseudocode:

```pseudocode
#| html-indent-size: "1.2em"
#| html-comment-delimiter: "//"
#| html-line-number: true
#| html-line-number-punc: ":"
#| html-no-end: false
#| pdf-placement: "htb!"
#| pdf-line-number: true
#| pdf-comment-delimiter: "//"

\begin{algorithm}
\caption{Quicksort}
\begin{algorithmic}
\Procedure{Quicksort}{$A, p, r$}
  \If{$p < r$}
    \State $q = $ \Call{Partition}{$A, p, r$}
    \State \Call{Quicksort}{$A, p, q - 1$}
    \State \Call{Quicksort}{$A, q + 1, r$}
  \EndIf
\EndProcedure
\Procedure{Partition}{$A, p, r$}
  \State $x = A[r]$
  \State $i = p - 1$
  \For{$j = p$ \To $r - 1$}
    \If{$A[j] < x$}
      \State $i = i + 1$
      \State exchange
      $A[i]$ with     $A[j]$
    \EndIf
    \State exchange $A[i]$ with $A[r]$
  \EndFor
\EndProcedure
\end{algorithmic}
\end{algorithm}
```

[!IMPORTANT] Use upper camel case format keyword rather than all uppercase format keyword.

Parameters

Global parameters are show as below:

Add global parameters in the header of your document, or in the _quarto.yml file:

pseudocode:
  caption-prefix: "Algorithm"
  reference-prefix: "Algorithm"
  caption-number: true
  caption-align: "left"

Parameters for pseudocode share the same format like R or Python code:

[!NOTE]

1. If set the placement in pseudocode, such as \begin{algorithm}[htb!], then pdf-placement option will be ignored.
2. If set show line number or not in pseudocode, such as \begin{algorithmic}[1], then pdf-line-number option will be ignored.
3. All these changes won't affect the output of HTML document. We recommend you set the parameters rather than modify pseudocode directly.

For HTML document, pseudocode.js render math formulas using either KaTeX or MathJax. We add pseudocode.js after html body, thus you need initialize KaTeX or MathJax before html body or in html header. Add this in the header of your document, or in the _quarto.yml file.

MathJax 3

format:
  html:
    include-in-header:
      text: |
        <script>
        MathJax = {
          loader: {
            load: ["[tex]/boldsymbol"],
          },
          tex: {
            tags: "all",
            inlineMath: [["$", "$"], ["\\(", "\\)"]],
            displayMath: [["$$", "$$"], ["\\[", "\\]"]],
            processEscapes: true,
            processEnvironments: true,
            packages: {
              "[+]": ["boldsymbol"],
            },
          },
        };
        </script>
        <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml-full.js"></script>

MathJax 4

format:
  html:
    include-in-header:
      text: |
        <script>
        MathJax = {
          loader: {
            load: ["[tex]/boldsymbol"],
          },
          tex: {
            tags: "all",
            inlineMath: [["$", "$"], ["\\(", "\\)"]],
            displayMath: [["$$", "$$"], ["\\[", "\\]"]],
            processEscapes: true,
            processEnvironments: true,
            packages: {
              "[+]": ["boldsymbol"],
            },
          },
        };
        </script>
        <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/mathjax@4/tex-chtml.js"></script>

KaTeX

format:
  html:
    include-in-header:
      text: |
      <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/katex@latest/dist/katex.min.css" />
      <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/katex@latest/dist/katex.min.js"></script>

For PDF document, pseudocode caption in book type project will be changed from Algorithm n to Algorithm x.n in chapter x. Add \algrenewcommand{\algorithmiccomment}[1]{<your value> #1} in the header of your document, or in the _quarto.yml file will change the form in which comments are displayed:

format:
  pdf:
    include-before-body:
      text: |
        \algrenewcommand{\algorithmiccomment}[1]{\hskip3em$\rightarrow$ #1}

Cross Reference

Build-in Cross Reference

Set the label in pseudocode, and it must start with algo-:

[!WARNING] From Quarto 1.8, alg has become a reserved cross reference prefix keyword.

```pseudocode
#| label: algo-quicksort
...

\begin{algorithm}
\caption{Quicksort}
\begin{algorithmic}
...
\end{algorithmic}
\end{algorithm}
```

Use @<label> to do cross reference:

Quicksort algorithm is shown as @algo-quicksort.

[!IMPORTANT] Must set label and \caption{} to make build-in cross reference works.

[!WARNING] For book type project, build-in cross reference in different files works only with PDF format.

Quarto Custom Cross Reference

Add custom cross reference for pseudocode in the header of your document, or in the _quarto.yml file:

crossref:
  custom:
    - kind: float
      key: alg
      reference-prefix: "Algorithm"
      caption-prefix: "Algorithm"
      latex-env: alg
      latex-list-of-description: Algorithm

Use Quarto custom cross reference to surround the pseudocode:

::: {#alg-quicksort}

```pseudocode
...

\begin{algorithm}
\caption{Quicksort}
\begin{algorithmic}
...
\end{algorithmic}
\end{algorithm}
```

Quicksort

:::

[!IMPORTANT]

1. Do not set label to avoid conflict with build-in cross reference.
2. Set the global parameter caption-number to false to avoid show different numbers in pseudocode build-in caption and Quarto cross reference caption.
3. Set both captions in pseudocode and Quarto custom cross reference to achieve best effect.

Use @<label> to do cross reference.

Quicksort algorithm is shown as @alg-quicksort.

Difference

1. Quarto custom cross reference will add an extra caption like figure, in which number may not be same as pseudocode build-in caption.
2. Build-in cross reference in different files is only available with PDF document for book type project. Quarto custom cross reference works in both HTML and PDF document.

Now, expect cross reference in different files with PDF document for book type project, we strongly recommend use build-in cross reference to achieve best effect.

[!CAUTION] Do not use different type of cross reference in the same project.

Examples

Pseudocode and cross reference rendered in HTML and PDF document are shown as below.

More examples please refer:

1. Single document (HTML and PDF): examples/simple.
2. Book document (HTML and PDF): examples/book.
3. Cross reference example (HTML and PDF): examples/cross-reference.
4. Beamer presentation (PDF): examples/beamer.
5. Revealjs presentation (HTML): examples/revealjs.

License

The MIT License (MIT)

Copyright (c) 2023-2026 范叶亮 | Leo Van