fix batch size update unintentional change

src/pydvl/value/semivalues.py

@@ -241,7 +241,7 @@ def compute_values(self) -> np.ndarray:
 
     def __call__(
         self, future_result: List[Tuple[List[IndexT], float]]
-    ) -> Tuple[MarginalT, ...]:
+    ) -> List[List[MarginalT, ...]]:
         """Computation of marginal utility using Maximum Sample Reuse.
 
         This processor requires the Marginal Function to be set to RawUtility.
@@ -259,8 +259,8 @@ def __call__(
             A collection of marginals. Each marginal is a tuple with index and its marginal
             utility.
         """
-        marginals: List[MarginalT] = []
-        for s, evaluation in future_result:
+        marginals: List[List[MarginalT]] = []
+        for batch_id, (s, evaluation) in enumerate(future_result):
             previous_values = self.compute_values()
             self.total_evaluations += 1
             self.point_in_subset[s] += 1
@@ -273,9 +273,12 @@ def __call__(
                 self.total_evaluations * new_values
                 - (self.total_evaluations - 1) * previous_values
             )
+            marginals.append([])
             for data_index in range(self.n):
-                marginals.append((data_index, float(marginal_vals[data_index])))
-        return tuple(marginals)
+                marginals[batch_id].append(
+                    (data_index, float(marginal_vals[data_index]))
+                )
+        return marginals
 
 
 # @deprecated(
@@ -373,11 +376,18 @@ def compute_generic_semivalues(
 
             completed, pending = wait(pending, timeout=1, return_when=FIRST_COMPLETED)
             for future in completed:
-                processed_future = future_processor(future.result())
-                for idx, marginal_val in processed_future:
-                    result.update(idx, marginal_val)
-                if done(result):
-                    return result
+                processed_future = future_processor(
+                    future.result()
+                )  # List of tuples or
+                for batch_future in processed_future:
+                    if isinstance(batch_future, list):  # Case when batch size is > 1
+                        for idx, marginal_val in batch_future:
+                            result.update(idx, marginal_val)
+                    else:  # Batch size 1
+                        idx, marginal_val = batch_future
+                        result.update(idx, marginal_val)
+                    if done(result):
+                        return result
 
             # Ensure that we always have n_submitted_jobs running
             try: