simplify

src/datasets/arrow_dataset.py

@@ -3352,15 +3352,12 @@ def apply_function_on_filtered_inputs(pa_inputs, indices, check_same_num_example
                 validate_function_output(processed_inputs, indices)
             if not update_data:
                 return None  # Nothing to update, let's move on
-            if shard._format_type or input_columns:
-                # TODO(QL, MS): ideally the behavior should be the same even if the dataset is formatted (may require major release)
-                inputs_to_merge = dict(zip(pa_inputs.column_names, pa_inputs.itercolumns()))
-            elif isinstance(inputs, LazyDict):
+            if isinstance(inputs, LazyDict):
                 inputs_to_merge = {
                     k: (v if k not in inputs.keys_to_format else pa_inputs[k]) for k, v in inputs.data.items()
                 }
             else:
-                inputs_to_merge = inputs
+                inputs_to_merge = dict(zip(pa_inputs.column_names, pa_inputs.itercolumns()))
             if remove_columns is not None:
                 for column in remove_columns:
                     # `function` can modify input in-place causing column to be already removed.