Fix: properly allow multiple inits in Pathfinder

Author: WardBrian

cmdstanpy/cmdstan_args.py

@@ -930,6 +930,7 @@ def validate(self) -> None:
                 if not (
                     isinstance(self.method_args, SamplerArgs)
                     and self.method_args.num_chains > 1
+                    or isinstance(self.method_args, PathfinderArgs)
                 ):
                     if not os.path.exists(self.inits):
                         raise ValueError('no such file {}'.format(self.inits))

test/test_pathfinder.py

@@ -2,6 +2,8 @@
     Tests for the Pathfinder method.
 """
 
+import contextlib
+from io import StringIO
 from pathlib import Path
 
 import numpy as np
@@ -129,6 +131,26 @@ def test_pathfinder_init_sampling():
     assert fit.draws().shape == (1000, 4, 9)
 
 
+def test_inits_for_pathfinder():
+    stan = DATAFILES_PATH / 'bernoulli.stan'
+    bern_model = cmdstanpy.CmdStanModel(stan_file=stan)
+    jdata = str(DATAFILES_PATH / 'bernoulli.data.json')
+    bern_model.pathfinder(
+        jdata, inits=[{"theta": 0.1}, {"theta": 0.9}], num_paths=2
+    )
+
+    # second path is initialized too large!
+    with contextlib.redirect_stdout(StringIO()) as captured:
+        bern_model.pathfinder(
+            jdata,
+            inits=[{"theta": 0.1}, {"theta": 1.1}],
+            num_paths=2,
+            show_console=True,
+        )
+
+    assert "Bounded variable is 1.1" in captured.getvalue()
+
+
 def test_pathfinder_no_psis():
     stan = DATAFILES_PATH / 'bernoulli.stan'
     bern_model = cmdstanpy.CmdStanModel(stan_file=stan)