Data commit

Task/Modified-random-distribution/Go/modified-random-distribution.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+    "fmt"
+    "math"
+    "math/rand"
+    "strings"
+    "time"
+)
+
+func rng(modifier func(x float64) float64) float64 {
+    for {
+        r1 := rand.Float64()
+        r2 := rand.Float64()
+        if r2 < modifier(r1) {
+            return r1
+        }
+    }
+}
+
+func commatize(n int) string {
+    s := fmt.Sprintf("%d", n)
+    if n < 0 {
+        s = s[1:]
+    }
+    le := len(s)
+    for i := le - 3; i >= 1; i -= 3 {
+        s = s[0:i] + "," + s[i:]
+    }
+    if n >= 0 {
+        return s
+    }
+    return "-" + s
+}
+
+func main() {
+    rand.Seed(time.Now().UnixNano())
+    modifier := func(x float64) float64 {
+        if x < 0.5 {
+            return 2 * (0.5 - x)
+        }
+        return 2 * (x - 0.5)
+    }
+    const (
+        N              = 100000
+        NUM_BINS       = 20
+        HIST_CHAR      = "■"
+        HIST_CHAR_SIZE = 125
+    )
+    bins := make([]int, NUM_BINS) // all zero by default
+    binSize := 1.0 / NUM_BINS
+    for i := 0; i < N; i++ {
+        rn := rng(modifier)
+        bn := int(math.Floor(rn / binSize))
+        bins[bn]++
+    }
+
+    fmt.Println("Modified random distribution with", commatize(N), "samples in range [0, 1):\n")
+    fmt.Println("    Range           Number of samples within that range")
+    for i := 0; i < NUM_BINS; i++ {
+        hist := strings.Repeat(HIST_CHAR, int(math.Round(float64(bins[i])/HIST_CHAR_SIZE)))
+        fi := float64(i)
+        fmt.Printf("%4.2f ..< %4.2f  %s %s\n", binSize*fi, binSize*(fi+1), hist, commatize(bins[i]))
+    }
+}