Quarto Pseudocode Extension

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A Quarto extension to render pseudocode for html and pdf document. It's based on pseudocode.js for html document, algorithm and algpseudocode 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

\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:

| Parameter           | Default     | Format | Description                     |
| ------------------- | ----------- | ------ | ------------------------------- |
| `caption-prefix`    | "Algorithm" | all    | prefix for caption              |
| `reference-prefix`  | "Algorithm" | all    | prefix for reference            |
| `caption-number`    | true        | all    | show number in build-in caption |

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

```yml
pseudocode:
  caption-prefix: "Algorithm"
  reference-prefix: "Algorithm"
  caption-number: true

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

Parameter	Default	Format	Description
`label`		all	label for cross reference, must start with `alg-` if has
`html-indent-size`	"1.2 em"	`html`	`indentSize` in pseudocode.js
`html-comment-delimiter`	"//"	`html`	`commentDelimiter` in pseudocode.js
`html-line-number`	true	`html`	`lineNumber` in pseudocode.js
`html-line-number-punc`	":"	`html`	`lineNumberPunc`in pseudocode.js
`html-no-end`	false	`html`	`noEnd` in pseudocode.js
`pdf-placement`	"H"	`pdf`	placement of the pseudocode in text
`pdf-line-number`	true	`pdf`	show line number

[!NOTE]

If set the placement in pseudocode, such as \begin{algorithm}[htb!], then pdf-placement option will be ignored.

If set show line number or not in pseudocode, such as \begin{algorithmic}[1], then pdf-line-number option will be ignored.

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.

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 src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml-full.js" type="text/javascript"></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: |
        \numberwithin{algorithm}{chapter}
        \algrenewcommand{\algorithmiccomment}[1]{\hskip3em$\rightarrow$ #1}

Cross Reference

Build-in Cross Reference

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

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

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


Use `@<label>` to do cross reference:

Quicksort algorithm is shown as @alg-quicksort.


> [!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:

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

[!IMPORTANT] Do not set key to alg, which is used for build-in reference.

Use Quarto custom cross reference to surround the pseudocode:

::: {#algo-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-no-number` to `true` 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 @algo-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.

| `html` document                    | `pdf` document                    |
| :--------------------------------: | :-------------------------------: |
| ![](screenshots/html-document.png) | ![](screenshots/pdf-document.png) |

More examples please refer:

1. Single document (`html` and `pdf`): [examples/simple](examples/simple).
2. Book document (`html` and `pdf`): [examples/book](examples/book).
3. Beamer document (`pdf`): [examples/beamer](examples/beamer).
4. Cross reference example (`html` and `pdf`): [examples/cross-reference](examples/cross-reference).

## License

The MIT License (MIT)

Copyright (c) 2023-2024 [范叶亮 | Leo Van](https://leovan.me)

leovan / quarto-pseudocode

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