Function edgeEntropyScore

internal/graph/graph.go:1098–1117

edgeEntropyScore computes the entropy value for a set of edges coming in or out of a node. Entropy (as defined in information theory) refers to the amount of information encoded by the set of edges. A set of edges that have a more interesting distribution of samples gets a higher score.

(n *Node, edges EdgeMap, self int64)

// edges. A set of edges that have a more interesting distribution of
// samples gets a higher score.
func edgeEntropyScore(n *Node, edges EdgeMap, self int64) float64 {
	score := float64(0)
	total := self
	for _, e := range edges {
		if e.Weight > 0 {
			total += abs64(e.Weight)
		}
	}
	if total != 0 {
		for _, e := range edges {
			frac := float64(abs64(e.Weight)) / float64(total)
			score += -frac * math.Log2(frac)
		}
		if self > 0 {
			frac := float64(abs64(self)) / float64(total)
			score += -frac * math.Log2(frac)
		}
	}
	return score
}

// NodeOrder sets the ordering for a Sort operation
type NodeOrder int