Render a syntactic tree as a PNG image

Takes a syntactic tree and renders it using Quarto's Typst engine, exporting the result as a PNG image. Supports two rendering backends controlled by tree_notation:

Usage

arborize(
  tree,
  output = "syntactic-tree.png",
  dpi = 300,
  tree_notation = c("simple", "structured"),
  papersize = "a5",
  margin = "0.5cm",
  provenance = TRUE,
  overwrite = FALSE
)

Arguments

tree

A character string. For tree_notation = "simple", a bracket notation string e.g. "[S [NP] [VP]]". For tree_notation = "structured", a lingotree tree() call string.

output

A character string. Path to the output PNG file. Defaults to "syntactic-tree.png" in the current working directory.

dpi

A numeric value. Resolution of the output PNG in dots per inch. Defaults to 300. Use 600 for print-quality output.

tree_notation

A character string. One of "simple" (default) or "structured". Controls which Typst rendering backend is used. See Details.

papersize

A character string. Typst paper size for the intermediate PDF. Defaults to "a5". Increase to "a4" for very wide trees.

margin

A character string. Page margin for the intermediate PDF. Defaults to "0.5cm". Reduce for tighter crops around the tree.

provenance

A logical. Whether to write a companion .yaml file recording the tree string and all rendering arguments alongside the PNG. Defaults to TRUE. The provenance file has the same name as the PNG but with a .yaml extension and lives in the same directory. Pass FALSE to suppress it.

overwrite

A logical. Whether to overwrite existing output files. When TRUE, overwrites both the PNG and the provenance file if they exist. Defaults to FALSE.

Value

Invisibly returns the path to the output PNG file.

Details

• "simple" uses @preview/syntree and accepts a bracket notation string, e.g. "[S [NP [Det the] [N cat]] [VP [V sat]]]". This is the most compact input format and suits basic linguistic trees.

• "structured" uses @preview/lingotree and accepts a nested tree() call string. This backend supports per-node styling, movement arrows, and multi-dominant trees.

The function is useful for producing standalone tree figures that can be embedded in any document format – LaTeX, Word, HTML, or presentations – without requiring a full LaTeX installation.

arborize() performs the following steps:

1. Validates inputs and resolves the Typst package from tree_notation.

2. Builds a minimal .qmd document via .build_arborize_qmd().

3. Writes the document and renders it inside a self-cleaning temporary directory managed by withr::with_tempdir().

4. Calls quarto::quarto_render() to produce an intermediate PDF via Typst.

5. Converts the PDF to PNG using pdftools::pdf_convert().

6. Reads the PNG bytes into memory before the temporary directory is deleted, then writes them to the specified output path.

7. If provenance = TRUE, writes a companion .yaml file recording the tree string and all rendering arguments.

On first use, Typst will download the required package from the Typst package registry. This requires an internet connection. Subsequent renders use the locally cached package.

Requires Quarto 1.4 or later with Typst support, and the pdftools package for PDF-to-PNG conversion. Install pdftools with install.packages("pdftools").

References

syntree Typst package (v0.2.1): https://typst.app/universe/package/syntree

lingotree Typst package (v1.0.0): https://typst.app/universe/package/lingotree

Examples

if (FALSE) { # \dontrun{
# Simple bracket notation (default) -- also writes tree-1.yaml
arborize("[NP [Det the] [N cat]]", output = "my-trees/tree-1.png")

# Suppress provenance file
arborize("[NP [Det the] [N cat]]", provenance = FALSE)

# Wider tree with print-quality output
arborize(
  paste0(
    "[Aspectual Classes ",
    "[Statives [States]] ",
    "[Dynamic ",
    "[Atelic [Activities]] ",
    "[Telic ",
    "[Instantaneous [Achievements]] ",
    "[Durative [Accomplishments]]]]]"
  ),
  output    = "aspectual-classes.png",
  dpi       = 600,
  papersize = "a4"
)

# Structured notation using lingotree
arborize(
  "tree(
    tag: [VP],
    tree(
      tag: [DP],
      [every],
      [farmer]
    ),
    [smiled]
  )",
  tree_notation = "structured",
  output        = "vp-tree.png"
)
} # }