RosettaCodeData/Task/Probabilistic-choice/Go/probabilistic-choice.go

64 lines
1.4 KiB
Go

package main
import (
"fmt"
"math/rand"
"time"
)
type mapping struct {
item string
pr float64
}
func main() {
// input mapping
m := []mapping{
{"aleph", 1 / 5.},
{"beth", 1 / 6.},
{"gimel", 1 / 7.},
{"daleth", 1 / 8.},
{"he", 1 / 9.},
{"waw", 1 / 10.},
{"zayin", 1 / 11.},
{"heth", 1759 / 27720.}} // adjusted so that probabilities add to 1
// cumulative probability
cpr := make([]float64, len(m)-1)
var c float64
for i := 0; i < len(m)-1; i++ {
c += m[i].pr
cpr[i] = c
}
// generate
const samples = 1e6
occ := make([]int, len(m))
rand.Seed(time.Now().UnixNano())
for i := 0; i < samples; i++ {
r := rand.Float64()
for j := 0; ; j++ {
if r < cpr[j] {
occ[j]++
break
}
if j == len(cpr)-1 {
occ[len(cpr)]++
break
}
}
}
// report
fmt.Println(" Item Target Generated")
var totalTarget, totalGenerated float64
for i := 0; i < len(m); i++ {
target := m[i].pr
generated := float64(occ[i]) / samples
fmt.Printf("%6s %8.6f %8.6f\n", m[i].item, target, generated)
totalTarget += target
totalGenerated += generated
}
fmt.Printf("Totals %8.6f %8.6f\n", totalTarget, totalGenerated)
}