Add new Hamming-adjacent neighborhood method to Searchspace

Author: stijnh

kernel_tuner/searchspace.py

@@ -20,7 +20,7 @@
 from kernel_tuner.util import check_restrictions as check_instance_restrictions
 from kernel_tuner.util import compile_restrictions, default_block_size_names
 
-supported_neighbor_methods = ["strictly-adjacent", "adjacent", "Hamming"]
+supported_neighbor_methods = ["strictly-adjacent", "adjacent", "Hamming", "Hamming-adjacent"]
 
 
 class Searchspace:
@@ -44,6 +44,7 @@ def __init__(
             strictly-adjacent: differs +1 or -1 parameter index value for each parameter
             adjacent: picks closest parameter value in both directions for each parameter
             Hamming: any parameter config with 1 different parameter value is a neighbor
+            Hamming-adjacent: differs +1 or -1 parameter index value for exactly 1 parameter.
         Optionally sort the searchspace by the order in which the parameter values were specified. By default, sort goes from first to last parameter, to reverse this use sort_last_param_first.
         """
         # set the object attributes using the arguments
@@ -552,6 +553,45 @@ def __get_neighbors_indices_hamming(self, param_config: tuple) -> List[int]:
         matching_indices = (num_matching_params == self.num_params - 1).nonzero()[0]
         return matching_indices
 
+    def __get_neighbors_indices_hammingadjacent(self, param_config_index: int = None, param_config: tuple = None) -> List[int]:
+        """Get the neighbors using adjacent distance from the parameter configuration (parameter index absolute difference >= 1)."""
+        param_config_value_indices = (
+            self.get_param_indices(param_config)
+            if param_config_index is None
+            else self.params_values_indices[param_config_index]
+        )
+
+        # compute boolean mask for all configuration that differ at exactly one parameter (Hamming distance == 1)
+        hamming_mask = np.count_nonzero(self.params_values_indices != param_config_value_indices, axis=1) == 1
+
+        # get the configuration indices of the hamming neighbors
+        hamming_indices, = np.nonzero(hamming_mask)
+
+        # for the hamming neighbors, calculate the difference between parameter value indices
+        hamming_index_difference = self.params_values_indices[hamming_mask] - param_config_value_indices
+
+        # for each parameter get the closest upper and lower parameter (absolute index difference >= 1)
+        # np.PINF has been replaced by 1e12 here, as on some systems np.PINF becomes np.NINF
+        upper_bound = np.min(
+            hamming_index_difference,
+            initial=1e12,
+            axis=0,
+            where=hamming_index_difference > 0,
+        )
+
+        lower_bound = np.max(
+            hamming_index_difference,
+            initial=-1e12,
+            axis=0,
+            where=hamming_index_difference < 0,
+        )
+
+        # return mask for adjacent neighbors (each parameter is within bounds)
+        adjacent_mask = np.all((lower_bound <= hamming_index_difference) & (hamming_index_difference <= upper_bound), axis=1)
+
+        # return hamming neighbors that are also adjacent
+        return hamming_indices[adjacent_mask]
+
     def __get_neighbors_indices_strictlyadjacent(
         self, param_config_index: int = None, param_config: tuple = None
     ) -> List[int]:
@@ -615,6 +655,13 @@ def __build_neighbors_index(self, neighbor_method) -> List[List[int]]:
         # for each parameter configuration, find the neighboring parameter configurations
         if self.params_values_indices is None:
             self.__prepare_neighbors_index()
+
+        if neighbor_method == "Hamming-adjacent":
+            return list(
+                self.__get_neighbors_indices_hammingadjacent(param_config_index, param_config)
+                for param_config_index, param_config in enumerate(self.list)
+            )
+
         if neighbor_method == "strictly-adjacent":
             return list(
                 self.__get_neighbors_indices_strictlyadjacent(param_config_index, param_config)
@@ -667,6 +714,8 @@ def get_neighbors_indices_no_cache(self, param_config: tuple, neighbor_method=No
             self.__prepare_neighbors_index()
 
         # if the passed param_config is fictious, we can not use the pre-calculated neighbors index
+        if neighbor_method == "Hamming-adjacent":
+            return self.__get_neighbors_indices_hammingadjacent(param_config_index, param_config)
         if neighbor_method == "strictly-adjacent":
             return self.__get_neighbors_indices_strictlyadjacent(param_config_index, param_config)
         if neighbor_method == "adjacent":

test/test_searchspace.py

@@ -245,6 +245,16 @@ def test_neighbors_hamming():
     __test_neighbors(test_config, expected_neighbors, "Hamming")
 
 
+def test_neighbors_hammingadjacent():
+    """Test whether the Hamming-adjacent neighbors are as expected."""
+    test_config = tuple([1, 4, "string_1"])
+    expected_neighbors = [
+        (1.5, 4, 'string_1'),
+    ]
+
+    __test_neighbors(test_config, expected_neighbors, "Hamming-adjacent")
+
+
 def test_neighbors_strictlyadjacent():
     """Test whether the strictly adjacent neighbors are as expected."""
     test_config = tuple([1, 4, "string_1"])
@@ -274,11 +284,19 @@ def test_neighbors_adjacent():
 def test_neighbors_fictious():
     """Test whether the neighbors are as expected for a fictious parameter configuration (i.e. not existing in the search space due to restrictions)."""
     test_config = tuple([1.5, 4, "string_1"])
+
     expected_neighbors_hamming = [
         (1.5, 4, 'string_2'),
         (1.5, 5.5, 'string_1'),
         (3, 4, 'string_1'),
     ]
+
+    expected_neighbors_hammingadjacent = [
+        (1.5, 4, 'string_2'),
+        (1.5, 5.5, 'string_1'),
+        (3, 4, 'string_1'),
+    ]
+
     expected_neighbors_strictlyadjacent = [
         (1.5, 5.5, 'string_2'),
         (1.5, 5.5, 'string_1'),
@@ -294,6 +312,7 @@ def test_neighbors_fictious():
     ]
 
     __test_neighbors_direct(test_config, expected_neighbors_hamming, "Hamming")
+    __test_neighbors_direct(test_config, expected_neighbors_hammingadjacent, "Hamming-adjacent")
     __test_neighbors_direct(test_config, expected_neighbors_strictlyadjacent, "strictly-adjacent")
     __test_neighbors_direct(test_config, expected_neighbors_adjacent, "adjacent")