Added placeholder/reminder to remove jax dependency when converting t…

…race data to InferenceData

pymc_experimental/inference/pathfinder/pathfinder.py

@@ -122,6 +122,7 @@ def convert_flat_trace_to_idata(
     samples,
     include_transformed=False,
     postprocessing_backend="cpu",
+    inference_backend="pymc",
     model=None,
 ):
     model = modelcontext(model)
@@ -139,10 +140,21 @@ def convert_flat_trace_to_idata(
     var_names = model.unobserved_value_vars
     vars_to_sample = list(get_default_varnames(var_names, include_transformed=include_transformed))
     print("Transforming variables...", file=sys.stdout)
-    jax_fn = get_jaxified_graph(inputs=model.value_vars, outputs=vars_to_sample)
-    result = jax.vmap(jax.vmap(jax_fn))(
-        *jax.device_put(list(trace.values()), jax.devices(postprocessing_backend)[0])
-    )
+
+    if inference_backend == "pymc":
+        # TODO: we need to remove JAX dependency as win32 users can now use Pathfinder with inference_backend="pymc".
+        jax_fn = get_jaxified_graph(inputs=model.value_vars, outputs=vars_to_sample)
+        result = jax.vmap(jax.vmap(jax_fn))(
+            *jax.device_put(list(trace.values()), jax.devices(postprocessing_backend)[0])
+        )
+    elif inference_backend == "blackjax":
+        jax_fn = get_jaxified_graph(inputs=model.value_vars, outputs=vars_to_sample)
+        result = jax.vmap(jax.vmap(jax_fn))(
+            *jax.device_put(list(trace.values()), jax.devices(postprocessing_backend)[0])
+        )
+    else:
+        raise ValueError(f"Invalid inference_backend: {inference_backend}")
+
     trace = {v.name: r for v, r in zip(vars_to_sample, result)}
     coords, dims = coords_and_dims_for_inferencedata(model)
     idata = az.from_dict(trace, dims=dims, coords=coords)
@@ -742,7 +754,6 @@ def fit_pathfinder(
             random_seed=random_seed,
             **pathfinder_kwargs,
         )
-
     elif inference_backend == "blackjax":
         jitter_seed, pathfinder_seed, sample_seed = _get_seeds_per_chain(random_seed, 3)
         # TODO: extend initial points initialisation to blackjax
@@ -773,15 +784,15 @@ def fit_pathfinder(
             state=pathfinder_state,
             num_samples=num_draws,
         )
-
     else:
-        raise ValueError(f"Inference backend {inference_backend} not supported")
+        raise ValueError(f"Invalid inference_backend: {inference_backend}")
 
     print("Running pathfinder...", file=sys.stdout)
 
     idata = convert_flat_trace_to_idata(
         pathfinder_samples,
         postprocessing_backend=postprocessing_backend,
+        inference_backend=inference_backend,
         model=model,
     )
     return idata