change default parameter to b

Author: farhanreynaldo

pymc3/distributions/continuous.py

@@ -3465,8 +3465,8 @@ class RiceRV(RandomVariable):
     _print_name = ("Rice", "\\operatorname{Rice}")
 
     @classmethod
-    def rng_fn(cls, rng, nu, sigma, size=None):
-        return stats.rice.rvs(b=nu / sigma, scale=sigma, size=size, random_state=rng)
+    def rng_fn(cls, rng, b, sigma, size=None):
+        return stats.rice.rvs(b=b, scale=sigma, size=size, random_state=rng)
 
 
 rice = RiceRV()
@@ -3539,10 +3539,10 @@ def dist(cls, nu=None, sigma=None, b=None, sd=None, *args, **kwargs):
             sigma = sd
 
         nu, b, sigma = cls.get_nu_b(nu, b, sigma)
-        nu = at.as_tensor_variable(floatX(nu))
+        b = at.as_tensor_variable(floatX(b))
         sigma = at.as_tensor_variable(floatX(sigma))
 
-        return super().dist([nu, sigma], *args, **kwargs)
+        return super().dist([b, sigma], *args, **kwargs)
 
     @classmethod
     def get_nu_b(cls, nu, b, sigma):
@@ -3556,7 +3556,7 @@ def get_nu_b(cls, nu, b, sigma):
             return nu, b, sigma
         raise ValueError("Rice distribution must specify either nu" " or b.")
 
-    def logp(value, nu, sigma):
+    def logp(value, b, sigma):
         """
         Calculate log-probability of Rice distribution at specified value.
 
@@ -3570,12 +3570,10 @@ def logp(value, nu, sigma):
         -------
         TensorVariable
         """
-        b = nu / sigma
         x = value / sigma
         return bound(
             at.log(x * at.exp((-(x - b) * (x - b)) / 2) * i0e(x * b) / sigma),
             sigma >= 0,
-            nu >= 0,
             value > 0,
         )
 

pymc3/tests/test_distributions_random.py

@@ -530,10 +530,10 @@ class TestSkewNormalTau(BaseTestDistribution):
 
 class TestRice(BaseTestDistribution):
     pymc_dist = pm.Rice
-    nu = sigma = 2
-    pymc_dist_params = {"nu": nu, "sigma": sigma}
-    expected_rv_op_params = {"nu": nu, "sigma": sigma}
-    reference_dist_params = {"b": nu / sigma, "scale": sigma}
+    b, sigma = 1, 2
+    pymc_dist_params = {"b": b, "sigma": sigma}
+    expected_rv_op_params = {"b": b, "sigma": sigma}
+    reference_dist_params = {"b": b, "scale": sigma}
     reference_dist = seeded_scipy_distribution_builder("rice")
     tests_to_run = [
         "check_pymc_params_match_rv_op",
@@ -542,11 +542,11 @@ class TestRice(BaseTestDistribution):
     ]
 
 
-class TestRiceB(BaseTestDistribution):
+class TestRiceNu(BaseTestDistribution):
     pymc_dist = pm.Rice
-    b, sigma = 1, 2
-    pymc_dist_params = {"b": b, "sigma": sigma}
-    expected_rv_op_params = {"nu": b * sigma, "sigma": sigma}
+    nu = sigma = 2
+    pymc_dist_params = {"nu": nu, "sigma": sigma}
+    expected_rv_op_params = {"b": nu / sigma, "sigma": sigma}
     tests_to_run = ["check_pymc_params_match_rv_op"]