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Task/Fibonacci-word/Go/fibonacci-word.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+// From http://rosettacode.org/wiki/Entropy#Go
+func entropy(s string) float64 {
+	m := map[rune]float64{}
+	for _, r := range s {
+		m[r]++
+	}
+	hm := 0.
+	for _, c := range m {
+		hm += c * math.Log2(c)
+	}
+	l := float64(len(s))
+	return math.Log2(l) - hm/l
+}
+
+const F_Word1 = "1"
+const F_Word2 = "0"
+
+func FibonacciWord(n int) string {
+	a, b := F_Word1, F_Word2
+	for ; n > 1; n-- {
+		a, b = b, b+a
+	}
+	return a
+}
+
+func FibonacciWordGen() <-chan string {
+	ch := make(chan string)
+	go func() {
+		a, b := F_Word1, F_Word2
+		for {
+			ch <- a
+			a, b = b, b+a
+		}
+	}()
+	return ch
+}
+
+func main() {
+	fibWords := FibonacciWordGen()
+	fmt.Printf("%3s %9s  %-18s  %s\n", "N", "Length", "Entropy", "Word")
+	n := 1
+	for ; n < 10; n++ {
+		s := <-fibWords
+		// Just to show the function and generator do the same thing:
+		if s2 := FibonacciWord(n); s != s2 {
+			fmt.Printf("For %d, generator produced %q, function produced %q\n", n, s, s2)
+		}
+		fmt.Printf("%3d %9d  %.16f  %s\n", n, len(s), entropy(s), s)
+	}
+	for ; n <= 37; n++ {
+		s := <-fibWords
+		fmt.Printf("%3d %9d  %.16f\n", n, len(s), entropy(s))
+	}
+}