Adding ability to generate a random normally distributed number

readme.md

@@ -123,6 +123,7 @@ Each of the generator properties (like `name`, `address`, and `lorem`) are calle
     randomNumber($nbDigits = NULL, $strict = false) // 79907610
     randomFloat($nbMaxDecimals = NULL, $min = 0, $max = NULL) // 48.8932
     numberBetween($min = 1000, $max = 9000) // 8567
+    normallyDistributedNumber($avg = 0, $sd = 1) // 2
     randomLetter            // 'b'
     // returns randomly ordered subsequence of a provided array
     randomElements($array = array ('a','b','c'), $count = 1) // array('c')

src/Faker/Generator.php

@@ -143,6 +143,7 @@
  * @method int randomNumber($nbDigits = null, $strict = false)
  * @method int|string|null randomKey(array $array = array())
  * @method int numberBetween($min = 0, $max = 2147483647)
+ * @method int normallyDistributedNumber($avg = 0, $sd = 1)
  * @method float randomFloat($nbMaxDecimals = null, $min = 0, $max = null)
  * @method mixed randomElement(array $array = array('a', 'b', 'c'))
  * @method array randomElements(array $array = array('a', 'b', 'c'), $count = 1, $allowDuplicates = false)

src/Faker/Provider/Base.php

@@ -139,6 +139,47 @@ public static function numberBetween($int1 = 0, $int2 = 2147483647)
         $max = $int1 < $int2 ? $int2 : $int1;
         return mt_rand($min, $max);
     }
+
+    /**
+     * Returns a random number normally distributed about the mean and standard deviation
+     *
+     * @param integer $avg
+     * @param integer $sd
+     *
+     * @return integer
+     */
+    public static function normallyDistributedNumber($avg = 0, $sd = 1)
+    {
+        $random_arrray = [];
+        $random_sign = [1, -1];
+
+        $sd2 = $sd*2;
+        $sd3 = $sd*3;
+        $sd4 = $sd*4;
+
+
+        for ($i=0; $i < 683; $i++) {
+            $random_number = $avg + (static::numberBetween(0, $sd) * $random_sign[array_rand($random_sign)]);
+            array_push($random_arrray, $random_number);
+        }
+
+        for ($i=0; $i < 271; $i++) {
+            $random_number = $avg + (static::numberBetween($sd, $sd2) * $random_sign[array_rand($random_sign)]);
+            array_push($random_arrray, $random_number);
+        }
+
+        for ($i=0; $i < 43; $i++) {
+            $random_number = $avg + (static::numberBetween($sd2, $sd3) * $random_sign[array_rand($random_sign)]);
+            array_push($random_arrray, $random_number);
+        }
+
+        for ($i=0; $i < 3; $i++) {
+            $random_number = $avg + (static::numberBetween($sd3, $sd4) * $random_sign[array_rand($random_sign)]);
+            array_push($random_arrray, $random_number);
+        }
+
+        return $random_arrray[array_rand($random_arrray)];
+    }
 
     /**
      * Returns the passed value