dot - little helper package in Go for the graphviz dot language

DOT language

package main

import (
	"fmt"	
	"github.com/emicklei/dot"
)

// go run main.go | dot -Tpng  > test.png && open test.png

func main() {
	g := dot.NewGraph(dot.Directed)
	n1 := g.Node("coding")
	n2 := g.Node("testing a little").Box()

	g.Edge(n1, n2)
	g.Edge(n2, n1, "back").Attr("color", "red")

	fmt.Println(g.String())
}

Output

digraph {
	node [label="coding"]; n1;
	node [label="testing a little",shape="box"]; n2;
	n1 -> n2;
	n2 -> n1 [color="red", label="back"];
}

Chaining edges

g.Node("A").Edge(g.Node("B")).Edge(g.Node("C"))

A -> B -> C

g.Node("D").BidirectionalEdge(g.Node("E"))

D <-> E

Subgraphs

s := g.Subgraph("cluster")
s.Attr("style", "filled")

Initializers

g := dot.NewGraph(dot.Directed)
g.NodeInitializer(func(n dot.Node) {
	n.Attr("shape", "rectangle")
	n.Attr("fontname", "arial")
	n.Attr("style", "rounded,filled")
})

g.EdgeInitializer(func(e dot.Edge) {
	e.Attr("fontname", "arial")
	e.Attr("fontsize", "9")
	e.Attr("arrowsize", "0.8")
	e.Attr("arrowhead", "open")
})

HTML and Literal values

node.Attr("label", Literal(`"left-justified text\l"`))
graph.Attr("label", HTML("<B>Hi</B>"))

cluster example

di := dot.NewGraph(dot.Directed)
outside := di.Node("Outside")

// A
clusterA := di.Subgraph("Cluster A", dot.ClusterOption{})
insideOne := clusterA.Node("one")
insideTwo := clusterA.Node("two")

// B
clusterB := di.Subgraph("Cluster B", dot.ClusterOption{})
insideThree := clusterB.Node("three")
insideFour := clusterB.Node("four")

// edges
outside.Edge(insideFour).Edge(insideOne).Edge(insideTwo).Edge(insideThree).Edge(outside)

See also ext/Subsystem type for creating composition hierarchies.

record example

See record_test.go#ExampleNode_NewRecordBuilder.

About dot attributes

https://graphviz.gitlab.io/doc/info/attrs.html

display your graph

go run main.go | dot -Tpng  > test.png && open test.png

mermaid

Output a dot Graph using the mermaid syntax. Only Graph and Flowchart are supported. See MermaidGraph and MermaidFlowchart.

g := dot.NewGraph(dot.Directed)
...
fmt.Println(dot.MermaidGraph(g, dot.MermaidTopToBottom))

subgraphs in mermaid

flowchart LR;n8-->n3;subgraph one;n2("a1");n3("a2");n2-->n3;end;subgraph three;n8("c1");n9("c2");n8-->n9;end;subgraph two;n5("b1");n6("b2");n5-->n6;end;

Loading

mermaid specific attributes

attr	type	description
link	Edge	examples are {-->,-.->,--x,o--o}
shape	Node	examples are {MermaidShapeRound,MermaidShapeCircle,MermaidShapeTrapezoid}
style	Node	example is fill:#90EE90

extensions

See also package dot/dotx for types that can help in constructing complex graphs.

testing

go test -coverprofile=coverage.out ./...
go tool cover -html=coverage.out

(c) 2015-2023, http://ernestmicklei.com. MIT License.