Fix np.shuffle and wrong return type in searchspace samplers

CHANGELOG.md

@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
+- Fix `np.shuffle` crash and wrong return type in `Searchspace` distributed random and LHS samplers
 
 ## [1.5.0] - 2026-08-20
 - Kernel Tuner can now be used from Julia, [see KernelTuner.jl](https://github.com/KernelTuner/KernelTuner.jl)

kernel_tuner/searchspace.py

@@ -1267,13 +1267,13 @@ def get_distributed_random_sample_indices(self, num_samples: int, sampling_facto
             )
             num_samples = round(self.size / 2)
         if num_samples == self.size:
-            return np.shuffle([range(self.size)])
+            return np.random.permutation(self.size).tolist()
 
         # adjust the number of random samples if necessary
         sampling_factor = max(1, sampling_factor)
         num_random_samples = min(sampling_factor * num_samples, self.size)
         if num_random_samples == self.size or num_random_samples <= 1:
-            return self.get_random_sample(num_random_samples)
+            return self.get_random_sample_indices(num_samples).tolist()
         random_samples_indices = self.get_random_sample_indices(num_random_samples)
 
         # calculate the desired parameter configuration indices, starting at the edges of the parameter indices and halving each time
@@ -1340,7 +1340,7 @@ def get_LHS_sample_indices(self, num_samples: int) -> List[int]:
             )
             num_samples = round(self.size / 2)
         if num_samples == self.size:
-            return np.shuffle([range(self.size)])
+            return np.random.permutation(self.size).tolist()
         if self.params_values_indices is None:
             self.__prepare_neighbors_index()
 

test/test_searchspace.py

@@ -9,6 +9,7 @@
     from unittest.mock import patch
 
 import numpy as np
+import pytest
 from constraint import ExactSumConstraint
 
 from kernel_tuner.interface import Options
@@ -562,6 +563,19 @@ def test_get_distributed_random_sample():
     for index in distributed_random_sample_indices:
         assert 0 <= index < searchspace.size
 
+    # check that requesting exactly the searchspace size returns every index exactly once
+    full_sample_indices = searchspace.get_distributed_random_sample_indices(num_samples=searchspace.size)
+    assert len(full_sample_indices) == searchspace.size
+    assert sorted(full_sample_indices) == list(range(searchspace.size))
+
+    # check that requesting more than the searchspace size warns and reduces the sample size
+    with pytest.warns(UserWarning):
+        oversized_sample_indices = searchspace.get_distributed_random_sample_indices(num_samples=searchspace.size + 6)
+    assert len(oversized_sample_indices) == round(searchspace.size / 2)
+    assert len(set(oversized_sample_indices)) == len(oversized_sample_indices)
+    for index in oversized_sample_indices:
+        assert 0 <= index < searchspace.size
+
 def test_get_LHS_sample_indices():
     """Test whether the distributed random sample indices are as expected."""
     # create a searchspace with mixed parameter types
@@ -588,6 +602,19 @@ def test_get_LHS_sample_indices():
     for index in distributed_random_sample_indices:
         assert 0 <= index < searchspace.size
 
+    # check that requesting exactly the searchspace size returns every index exactly once
+    full_sample_indices = searchspace.get_LHS_sample_indices(num_samples=searchspace.size)
+    assert len(full_sample_indices) == searchspace.size
+    assert sorted(full_sample_indices) == list(range(searchspace.size))
+
+    # check that requesting more than the searchspace size warns and reduces the sample size
+    with pytest.warns(UserWarning):
+        oversized_sample_indices = searchspace.get_LHS_sample_indices(num_samples=searchspace.size + 6)
+    assert len(oversized_sample_indices) == round(searchspace.size / 2)
+    assert len(set(oversized_sample_indices)) == len(oversized_sample_indices)
+    for index in oversized_sample_indices:
+        assert 0 <= index < searchspace.size
+
 def test_small_searchspace():
     """Test a small real-world searchspace and the usage of the `max_threads` parameter."""
     max_threads = 1024