Label Prefix System

Cross-References

Quarto provides a unified cross-reference system for figures, tables, equations, sections, theorems, and more.

Label Prefix System

All cross-referenceable elements require a label starting with a type prefix:

Recommended Syntax

For consistency, prefer using div syntax for cross-referenceable elements:

::: {#tbl-example}

| Column 1 | Column 2 |
| -------- | -------- |
| Data     | Data     |

Table caption.
:::

Instead of inline caption syntax:

| Column 1 | Column 2 |
| -------- | -------- |
| Data     | Data     |

: Table caption. {#tbl-example}

Both syntaxes work, but div syntax provides a more consistent pattern across all element types (figures, tables, theorems, etc.).

Reference Syntax

Use @ followed by the label to create a reference:

See @fig-plot for the visualization.
The data is shown in @tbl-results.
As discussed in @sec-methods, we used...

Capitalization

Use capital letter to get capitalized prefix:

@fig-plot → Figure 1
@Fig-plot → Figure 1 (same, but ensures capital)

Prefix Customization

Use square brackets for custom prefix:

[Figure @fig-plot] → Figure 1
[See @fig-plot] → See 1
[-@fig-plot] → 1 (number only)

Multiple References

See @fig-plot and @fig-scatter.
Tables [-@tbl-one; -@tbl-two] show...

Figures

Code-Generated Figures

```{r}
#| label: fig-scatter
#| fig-cap: "Scatter plot of x versus y."

plot(x, y)
```

Reference: See @fig-scatter.

Markdown Figures

![Elephant](elephant.png){#fig-elephant}

See @fig-elephant for the image.

Subfigures

::: {#fig-animals layout-ncol=2}

![Cat](cat.png){#fig-cat}

![Dog](dog.png){#fig-dog}

Comparison of animals.
:::

See @fig-animals, specifically @fig-cat.

Tables

Code-Generated Tables

```{r}
#| label: tbl-summary
#| tbl-cap: "Summary statistics."

knitr::kable(summary_data)
```

Reference: `See @tbl-summary.`

Markdown Tables

::: {#tbl-data}

| Col 1 | Col 2 |
| ----- | ----- |
| A     | B     |

Summary data.
:::

See @tbl-data for details.

Subtables

::: {#tbl-panel layout-ncol=2}

::: {#tbl-first}

| Col A |
| ----- |
| 1     |

First table.
:::

::: {#tbl-second}

| Col B |
| ----- |
| 2     |

Second table.
:::

Combined tables.
:::

See @tbl-panel, including @tbl-first.

Sections

Enable numbered sections to reference them:

number-sections: true

Add label to heading:

## Introduction {#sec-intro}

As discussed in @sec-intro...

Equations

$$
y = mx + b
$$ {#eq-line}

Equation @eq-line shows...
$$

Theorems and Proofs

::: {#thm-pythagorean}

## Pythagorean Theorem

For a right triangle with legs $a$ and $b$ and hypotenuse $c$:
$$a^2 + b^2 = c^2$$
:::

By @thm-pythagorean, we know...

Available theorem types: thm, lem, cor, prp, cnj, def, exm, exr.

Code Listings

```{#lst-example .python lst-cap="Example Python code"}
def hello():
    print("Hello, world!")
```

See @lst-example for the code.

Callouts

Make callouts cross-referenceable by adding an ID:

::: {#nte-important .callout-note}

## Important Note

This is cross-referenceable.
:::

See @nte-important for details.

Custom Cross-Reference Types

Define custom types in YAML:

crossref:
  custom:
    - kind: float
      key: vid
      reference-prefix: "Video"
      caption-prefix: "Video"

Use:

::: {#vid-demo}
<video src="demo.mp4"></video>

Demo video.
:::

See @vid-demo.

Cross-Reference Options

Configure in YAML front matter:

crossref:
  fig-title: "Figure" # Prefix for figures
  tbl-title: "Table" # Prefix for tables
  eq-prefix: "Equation" # Prefix for equations
  sec-prefix: "Section" # Prefix for sections
  fig-prefix: "Figure" # In-text prefix
  tbl-prefix: "Table" # In-text prefix
  chapters: true # Number by chapter

Localization

lang: de
crossref:
  fig-title: "Abbildung"
  tbl-title: "Tabelle"

For bookdown migration details, see conversion-bookdown.md.

Resources

• Quarto Cross-References
• Figures
• Tables