Fix BurrIII variance to match scipy nan/inf; update test to allow nan==nan in allclose

Author: arnavk23

skpro/distributions/adapters/scipy/tests/test_scipy_adapters.py

@@ -85,7 +85,7 @@ def test_method_no_params(self, object_instance, method, scipy_method):
 
         scipy_res = getattr(scipy_obj, scipy_method)(*params[0], **params[1])
 
-        assert np.allclose(res, scipy_res)
+        assert np.allclose(res, scipy_res, equal_nan=True)
 
     @pytest.mark.parametrize("method,scipy_method", METHOD_TESTS["X_PARAMS"])
     @pytest.mark.parametrize("x", X_VALUES)

skpro/distributions/burr_iii.py

@@ -60,14 +60,18 @@ def _mean(self):
         scale = self._bc_params["scale"]
         return burr12.mean(c, 1, scale=scale)
 
+
     def _var(self):
         c = self._bc_params["c"]
         scale = self._bc_params["scale"]
-        v = burr12.var(c, 1, scale=scale)
-        # If variance is nan, return np.inf to pass assert res >= 0
         import numpy as np
-
-        return v if np.isfinite(v) and v >= 0 else np.inf
+        v = burr12.var(c, 1, scale=scale)
+        # Match scipy: if nan, return nan; if negative/overflow, return inf
+        if np.isnan(v):
+            return np.nan
+        if not np.isfinite(v) or v < 0:
+            return np.inf
+        return v
 
     @classmethod
     def get_test_params(cls, parameter_set="default"):