Force risk to be non-negative (growthbook#939)

* Force risk to be non-negative * lint
leugin · Jan 25, 2023 · 199675f · 199675f
1 parent b33a6ec
commit 199675f
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diff --git a/packages/stats/gbstats/bayesian/dists.py b/packages/stats/gbstats/bayesian/dists.py
@@ -61,7 +61,7 @@ def risk(cls, a_par1, a_par2, b_par1, b_par2, n=24):
         )
         out = gq - cls.dist.mean((a_par1, b_par1), (a_par2, b_par2))
 
-        return out
+        return np.maximum(out, 0)
 
 
 class Beta(BayesABDist):

diff --git a/packages/stats/tests/bayesian/test_dists.py b/packages/stats/tests/bayesian/test_dists.py
@@ -77,6 +77,12 @@ def test_gq(self):
                 roundsum(np.log(x) * w), roundsum(digamma(a) - digamma(a + b))
             )
 
+    def test_risk_nonnegative(self):
+        # Test used to fail before solution to GH issue
+        risk = Beta.risk(5563, 1281, 4605, 2888).tolist()
+        for r in risk:
+            self.assertGreaterEqual(r, 0)
+
 
 class TestNorm(TestCase):
     def test_posterior(self):