add test for modes (#613)

preliz/distributions/asymmetric_laplace.py

@@ -139,6 +139,9 @@ def median(self):
     def mean(self):
         return (1 / self.kappa - self.kappa) * self.b + self.mu
 
+    def mode(self):
+        return self.mu
+
     def var(self):
         return ((1 / self.kappa) ** 2 + self.kappa**2) * self.b**2
 

preliz/distributions/betabinomial.py

@@ -111,6 +111,13 @@ def entropy(self):
     def mean(self):
         return self.n * self.alpha / (self.alpha + self.beta)
 
+    def mode(self):
+        return np.clip(
+            np.floor((self.n + 1) * ((self.alpha - 1) / (self.alpha + self.beta - 2))).astype(int),
+            0,
+            self.n,
+        )
+
     def median(self):
         return self.ppf(0.5)
 

preliz/distributions/categorical.py

@@ -109,6 +109,9 @@ def entropy(self):
     def mean(self):
         return NotImplemented
 
+    def mode(self):
+        return self.p.argmax()
+
     def median(self):
         return NotImplemented
 

preliz/tests/test_scipy.py

@@ -325,3 +325,11 @@ def test_match_scipy(p_dist, sp_dist, p_params, sp_params):
         assert_almost_equal(actual_median, expected_median, decimal=6)
     else:
         assert_almost_equal(actual_median, expected_median)
+
+    finite_expected_pdf = np.where(np.isfinite(expected_pdf), expected_pdf, -np.inf)
+    expected_mode = extended_vals[np.argmax(finite_expected_pdf)]
+    try:
+        actual_mode = preliz_dist.mode()
+        assert_almost_equal(actual_mode, expected_mode, decimal=0)
+    except NotImplementedError:
+        pass