add variance to distribution

uravu/distribution.py

@@ -90,15 +90,34 @@ def n(self):
         return np.percentile(self.samples, [50])[0]
 
     @property
-    def s(self):
+    def s(self, ddof=1):
         """
         Get the standard deviation of the distribution. For a non-normal distribution, this will return :py:attr:`None`.
 
+        Args:
+            ddof (:py:attr:`int`): Degrees of freedom to be included in calculation.
+
+        Returns:
+            :py:attr:`float` or :py:attr:`None`: Standard deviation of the distribution.
+        """
+        if self.normal:
+            return np.std(self.samples, ddof=ddof)
+        else:
+            return None
+
+    @property
+    def v(self, ddof=1):
+        """
+        Get the variance of the distribution. For a non-normal distribution, this will return :py:attr:`None`.
+
+        Args:
+            ddof (:py:attr:`int`): Degrees of freedom to be included in calculation.
+
         Returns:
             :py:attr:`float` or :py:attr:`None`: Standard deviation of the distribution.
         """
         if self.normal:
-            return np.std(self.samples)
+            return np.var(self.samples, ddof=ddof)
         else:
             return None
 

uravu/tests/test_distribution.py

@@ -109,6 +109,14 @@ def test_check_normality_less_than_3(self):
         distro = Distribution(np.random.randn(2))
         assert_equal(distro.normal, False)
 
+    def test_s(self):
+        """
+        Test the standard deviation and variance
+        """
+        distro = Distribution(np.random.randn(10000) * 10)
+        assert_almost_equal(distro.s, 10., decimal=1)
+        assert_almost_equal(distro.v, 100., decimal=0)
+
     def test_add_samples_single(self):
         """
         Test add_samples with a single value.