Data update

Task/Statistics-Basic/Ballerina/statistics-basic.ballerina

@@ -0,0 +1,44 @@
+import ballerina/io;
+import ballerina/random;
+
+function mean(float[] a) returns float {
+    return float:sum(...a) / a.length();
+}
+
+function popStdDev(float[] a) returns float {
+    float m = mean(a);
+    var sumSq = function(float total, float next) returns float {
+                    return total + next * next;
+                };
+    return (a.reduce(sumSq, 0.0) / a.length() - m * m).sqrt();
+}
+
+function repeat(string s, int times) returns string {
+    string r = "";
+    foreach int i in 1...times { r += s; }
+    return r;
+}
+
+public function main() {
+    foreach int i in [100, 1000, 10000] {
+        float[] a = [];
+        a.setLength(i);
+        foreach int j in 0..<i { a[j] = random:createDecimal(); }
+        io:println(`For ${i} random numbers:`);
+        io:println("  mean    = ", mean(a));
+        io:println("  std/dev = ", popStdDev(a));
+        int scale = i / 100;
+        io:println("  scale   = ", scale, " per asterisk");
+        int[10] sums = [];
+        foreach float e in a {
+            int f = <int>(e*10).floor();
+            sums[f] += 1;
+        }
+        foreach int j in 0...8 {
+            sums[j] = <int>((<float>sums[j] / scale).round());
+            io:println(`  0.${j} - 0.${j+1}: `, repeat("*", sums[j]));
+        }
+        sums[9] = 100 - int:sum(...sums.slice(0, 9));
+        io:println("  0.9 - 1.0: ", repeat("*", sums[9]), "\n");
+    }
+}