Shannon's entropy measure of dataset heterogeneity

shannon.go

package main

import (
	"fmt"
	"math"
)

func main() {

	// set of probabilities
	// ex. you draw 12 cards
	// from a deck and organize
	// them by suits
	ps := []float64{
		(5. / 12.), // clubs
		(3. / 12.), // hearts
		(3. / 12.), // spades
		(1. / 12.), // diamonds
	}

	// measure dataset heterogeniety
	fmt.Println(H(ps))
}

// Shannon's entropy
func H(ps []float64) float64 {
	total := 0.0
	for _, p := range ps {
		p_log2 := math.Log2(p)
		total += p * p_log2
	}
	return -1.0 * total
}