yog/render/dot

DOT (Graphviz) format export for visualizing graphs.

This module exports graphs to the DOT language, which is the native format for Graphviz - a powerful open-source graph visualization tool. The exported files can be rendered to PNG, SVG, PDF, and other formats using the dot, neato, circo, or other Graphviz layout engines.

Quick Start

import yog/render/dot

// Export with default styling
let dot_string = dot.to_string(my_graph)

// Write to file and render with Graphviz CLI
// $ dot -Tpng output.dot -o graph.png

Customization

Use DotOptions to customize:

Node labels and shapes
Edge labels and styles
Highlight specific nodes or paths
Graph direction (LR, TB, etc.)

Rendering Options

Engine	Best For
`dot`	Hierarchical layouts (DAGs, trees)
`neato`	Spring-based layouts (undirected)
`circo`	Circular layouts
`fdp`	Force-directed layouts
`sfdp`	Large graphs

References

Types

ArrowStyle

</>

Arrow head/tail style

pub type ArrowStyle {
  Normal
  ArrowDot
  ArrowDiamond
  ODiamond
  ArrowBox
  Crow
  Vee
  Inv
  Tee
  ArrowNone
  CustomArrow(String)
}

Constructors

```
Normal
```
Standard arrow
```
ArrowDot
```
Dot circle
```
ArrowDiamond
```
Filled diamond
```
ODiamond
```
Empty diamond
```
ArrowBox
```
ArrowBox
```
Crow
```
Crow’s foot (database notation)
```
Vee
```
V-shaped
```
Inv
```
Inverted V
```
Tee
```
Tee (perpendicular line)
```
ArrowNone
```
No arrow
```
CustomArrow(String)
```
Custom arrow (e.g., “ediamond”, “odot”)

DotOptions

</>

Options for customizing DOT (Graphviz) diagram rendering.

pub type DotOptions {
  DotOptions(
    node_label: fn(Int, String) -> String,
    edge_label: fn(String) -> String,
    highlighted_nodes: option.Option(List(Int)),
    highlighted_edges: option.Option(List(#(Int, Int))),
    graph_name: String,
    layout: option.Option(Layout),
    rankdir: option.Option(RankDir),
    bgcolor: option.Option(String),
    splines: option.Option(Splines),
    overlap: option.Option(Overlap),
    nodesep: option.Option(Float),
    ranksep: option.Option(Float),
    node_shape: NodeShape,
    node_color: String,
    node_style: Style,
    node_fontname: String,
    node_fontsize: Int,
    node_fontcolor: String,
    edge_color: String,
    edge_style: Style,
    edge_fontname: String,
    edge_fontsize: Int,
    edge_penwidth: Float,
    arrowhead: option.Option(ArrowStyle),
    arrowtail: option.Option(ArrowStyle),
    highlight_color: String,
    highlight_penwidth: Float,
  )
}

Constructors

```
DotOptions(
  node_label: fn(Int, String) -> String,
  edge_label: fn(String) -> String,
  highlighted_nodes: option.Option(List(Int)),
  highlighted_edges: option.Option(List(#(Int, Int))),
  graph_name: String,
  layout: option.Option(Layout),
  rankdir: option.Option(RankDir),
  bgcolor: option.Option(String),
  splines: option.Option(Splines),
  overlap: option.Option(Overlap),
  nodesep: option.Option(Float),
  ranksep: option.Option(Float),
  node_shape: NodeShape,
  node_color: String,
  node_style: Style,
  node_fontname: String,
  node_fontsize: Int,
  node_fontcolor: String,
  edge_color: String,
  edge_style: Style,
  edge_fontname: String,
  edge_fontsize: Int,
  edge_penwidth: Float,
  arrowhead: option.Option(ArrowStyle),
  arrowtail: option.Option(ArrowStyle),
  highlight_color: String,
  highlight_penwidth: Float,
)
```
Arguments

node_label

Function to convert node ID and data to a display label

edge_label

Function to convert edge weight to a display label

highlighted_nodes

Optional list of node IDs to highlight

highlighted_edges

Optional list of edges to highlight as (from, to) pairs

graph_name

Graph name (default: “G”)

layout

Layout engine (default: None = auto-detect)

rankdir

Graph direction (default: Some(TopToBottom))

bgcolor

Background color (CSS color, default: None)

splines

Edge routing (default: None = Graphviz default)

overlap

Overlap handling (default: None)

nodesep

Minimum space between nodes in inches (default: 0.25)

ranksep

Minimum space between ranks in inches (default: 0.5)

node_shape

Node shape (default: Ellipse)

node_color

Default node fill color (CSS color)

node_style

Node style (default: Filled)

node_fontname

Node font name (default: “Helvetica”)

node_fontsize

Node font size in points (default: 12)

node_fontcolor

Node font color (CSS color, default: “black”)

edge_color

Default edge color (CSS color, default: “black”)

edge_style

Edge style (default: Solid)

edge_fontname

Edge font name (default: “Helvetica”)

edge_fontsize

Edge font size in points (default: 10)

edge_penwidth

Edge line thickness (default: 1.0)

arrowhead

Arrow head style (default: None = Graphviz default)

arrowtail

Arrow tail style (default: None)

highlight_color

Highlight color for nodes/edges (CSS color, default: “red”)

highlight_penwidth

Highlight pen width (default: 2.0)

Layout

</>

Graphviz layout engine

pub type Layout {
  Dot
  Neato
  Circo
  Fdp
  Sfdp
  Twopi
  Osage
  CustomLayout(String)
}

Constructors

```
Dot
```
Hierarchical layouts (DAGs, trees) - default for most use cases
```
Neato
```
Spring-based layouts (undirected graphs)
```
Circo
```
Circular layouts
```
Fdp
```
Force-directed placement
```
Sfdp
```
Scalable force-directed (for large graphs)
```
Twopi
```
Radial layouts
```
Osage
```
Clustered layouts (array-based)
```
CustomLayout(String)
```
Custom layout engine

NodeShape

</>

Node shapes

pub type NodeShape {
  Box
  Circle
  Ellipse
  Diamond
  Hexagon
  Pentagon
  Octagon
  Triangle
  Rectangle
  Square
  Rect
  InvTriangle
  House
  InvHouse
  Parallelogram
  Trapezoid
  CustomShape(String)
}

Constructors

```
Box
```
```
Circle
```
```
Ellipse
```
```
Diamond
```
```
Hexagon
```
```
Pentagon
```
```
Octagon
```
```
Triangle
```
```
Rectangle
```
```
Square
```
```
Rect
```
Rounded rectangle
```
InvTriangle
```
Inverted triangle
```
House
```
House shape (pentagon with flat top)
```
InvHouse
```
Inverted house
```
Parallelogram
```
Parallelogram
```
Trapezoid
```
Trapezoid
```
CustomShape(String)
```
Custom shape (for advanced Graphviz shapes)

Overlap

</>

Overlap handling

pub type Overlap {
  OverlapTrue
  OverlapFalse
  Scale
  ScaleXY
  Prism
  CustomOverlap(String)
}

Constructors

```
OverlapTrue
```
Allow overlaps (faster)
```
OverlapFalse
```
Remove all overlaps (slower)
```
Scale
```
Scale graph to remove overlaps
```
ScaleXY
```
Scale x and y independently
```
Prism
```
Prism algorithm (Voronoi-based)
```
CustomOverlap(String)
```
Custom overlap mode

RankDir

</>

Graph direction (rank direction)

pub type RankDir {
  TopToBottom
  LeftToRight
  BottomToTop
  RightToLeft
}

Constructors

```
TopToBottom
```
Top to Bottom (vertical, downward)
```
LeftToRight
```
Left to Right (horizontal)
```
BottomToTop
```
Bottom to Top (vertical, upward)
```
RightToLeft
```
Right to Left (horizontal, reversed)

Splines

</>

Edge routing style

pub type Splines {
  Line
  Polyline
  Curved
  Ortho
  Spline
  SplinesNone
}

Constructors

```
Line
```
Straight lines
```
Polyline
```
Polyline (bent lines)
```
Curved
```
Curved edges
```
Ortho
```
Orthogonal (right angles only)
```
Spline
```
Bezier splines (smooth curves) - Graphviz default
```
SplinesNone
```
No edges

Style

</>

Visual style

pub type Style {
  Solid
  Dashed
  Dotted
  Bold
  Filled
  Rounded
  Diagonals
  Striped
  Wedged
}

Constructors

```
Solid
```
```
Dashed
```
```
Dotted
```
```
Bold
```
```
Filled
```
```
Rounded
```
```
Diagonals
```
```
Striped
```
```
Wedged
```

Values

default_dot_options

</>

pub fn default_dot_options() -> DotOptions

Creates default DOT options with simple labeling and sensible styling.

Default configuration:

Layout: Auto-detected by Graphviz
Direction: Top-to-bottom
Node shape: Ellipse
Colors: Light blue nodes, black edges
Font: Helvetica 12pt

path_to_dot_options

</>

pub fn path_to_dot_options(
  path: utils.Path(e),
  base_options: DotOptions,
) -> DotOptions

Converts a shortest path result to highlighted DOT options.

to_dot

</>

pub fn to_dot(
  graph: model.Graph(String, String),
  options: DotOptions,
) -> String

Converts a graph to DOT (Graphviz) syntax.

The graph’s node data and edge data must be convertible to strings. Use the options to customize labels and highlighting.

Time Complexity: O(V + E)

Example

let graph =
  model.new(Directed)
  |> model.add_node(1, "Start")
  |> model.add_node(2, "Process")
  |> model.add_edge(from: 1, to: 2, with: "5")

let diagram = dot.to_dot(graph, default_dot_options())
// io.println(diagram)

This output can be processed by Graphviz tools (e.g., dot -Tpng -o graph.png):

digraph G {
  node [shape=ellipse];
  1 [label="Start"];
  2 [label="Process"];
  1 -> 2 [label="5"];
}

Quick Start

Customization

Rendering Options

References

Constructors

Constructors

Arguments

Constructors

Constructors

Constructors

Constructors

Constructors

Constructors

Example