Function ComposeDot

internal/graph/dotgraph.go:57–98

Number of nodelets for labels (both numeric and non) ComposeDot creates and writes a in the DOT format to the writer, using the configurations given.

(w io.Writer, g *Graph, a *DotAttributes, c *DotConfig)

// ComposeDot creates and writes a in the DOT format to the writer, using
// the configurations given.
func ComposeDot(w io.Writer, g *Graph, a *DotAttributes, c *DotConfig) {
	builder := &builder{w, a, c}

	// Begin constructing DOT by adding a title and legend.
	builder.start()
	defer builder.finish()
	builder.addLegend()

	if len(g.Nodes) == 0 {
		return
	}

	// Preprocess graph to get id map and find max flat.
	nodeIDMap := make(map[*Node]int)
	hasNodelets := make(map[*Node]bool)

	maxFlat := float64(abs64(g.Nodes[0].FlatValue()))
	for i, n := range g.Nodes {
		nodeIDMap[n] = i + 1
		if float64(abs64(n.FlatValue())) > maxFlat {
			maxFlat = float64(abs64(n.FlatValue()))
		}
	}

	edges := EdgeMap{}

	// Add nodes and nodelets to DOT builder.
	for _, n := range g.Nodes {
		builder.addNode(n, nodeIDMap[n], maxFlat)
		hasNodelets[n] = builder.addNodelets(n, nodeIDMap[n])

		// Collect all edges. Use a fake node to support multiple incoming edges.
		for _, e := range n.Out {
			edges[&Node{}] = e
		}
	}

	// Add edges to DOT builder. Sort edges by frequency as a hint to the graph layout engine.
	for _, e := range edges.Sort() {
		builder.addEdge(e, nodeIDMap[e.Src], nodeIDMap[e.Dest], hasNodelets[e.Src])
	}
}

// builder wraps an io.Writer and understands how to compose DOT formatted elements.
type builder struct {