tasks a-s

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

@@ -0,0 +1,63 @@
+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)
+}