Function graphFrom

plotter/contour.go:575–595

graphFrom returns a graph representing the point path p.

(p path)

// graphFrom returns a graph representing the point path p.
func graphFrom(p path) graph {
	g := make([]set, len(p))
	seen := make(map[point]int)
	for i, v := range p {
		if _, ok := seen[v]; !ok {
			seen[v] = i
		}
	}

	for i, v := range p {
		e, ok := seen[v]
		if ok && g[e] == nil {
			g[e] = make(set)
		}
		if i < len(p)-1 {
			g[e][seen[p[i+1]]] = struct{}{}
		}
	}

	return g
}

// subpath returns a subpath given the slice of point indices
// into the path.