Fix: autoregressive params info (#584)

* fix: autoregressive params info

* Add test

* make test less arbitrary

Co-authored-by: Jesse Grabowski <48652735+jessegrabowski@users.noreply.github.com>

* Fix typo

---------

Co-authored-by: Jesse Grabowski <48652735+jessegrabowski@users.noreply.github.com>

Author: AlexAndorra

pymc_extras/statespace/models/structural/components/autoregressive.py

@@ -141,19 +141,19 @@ def populate_component_properties(self):
 
         self.param_info = {
             f"params_{self.name}": {
-                "shape": (k_states,) if self.k_endog == 1 else (self.k_endog, k_states),
+                "shape": (k_endog_effective, k_states) if k_endog_effective > 1 else (k_states,),
                 "constraints": None,
                 "dims": (AR_PARAM_DIM,)
-                if self.k_endog == 1
+                if k_endog_effective == 1
                 else (
                     f"endog_{self.name}",
                     f"lag_{self.name}",
                 ),
             },
             f"sigma_{self.name}": {
-                "shape": () if self.k_endog == 1 else (self.k_endog,),
+                "shape": (k_endog_effective,) if k_endog_effective > 1 else (),
                 "constraints": "Positive",
-                "dims": None if self.k_endog == 1 else (f"endog_{self.name}",),
+                "dims": (f"endog_{self.name}",) if k_endog_effective > 1 else None,
             },
         }
 

tests/statespace/models/structural/components/test_autoregressive.py

@@ -163,6 +163,14 @@ def test_autoregressive_shared_and_not_shared():
         observed_state_names=["data_1", "data_2", "data_3"],
         share_states=True,
     )
+
+    # make sure param_info is correct
+    # shound't have endog state when share_states is True
+    assert not any(
+        dim.startswith("endog_") for dim in shared.param_info["params_shared_ar"]["dims"]
+    )
+    assert shared.param_info["sigma_shared_ar"]["dims"] is None
+
     individual = st.AutoregressiveComponent(
         order=3,
         name="individual_ar",