[{'role': 'system', 'content': "You are an expert in machine learning and your task is to classify code snippets into one of the following categories: ['helper_functions', 'load_data', 'data_exploration', 'data_preprocessing', 'evaluation', 'modelling', 'prediction', 'result_visualization', 'save_results', 'comment_only']."}, {'role': 'user', 'content': 'Identify the single most appropriate category to which the provided code belongs. Provide your response as a single category label without any additional information, commentary, or personal opinions.\\nPython Code:test_set_rf_cont = test_set_rf[cont_vars]\n\nscaler.fit(test_set_rf_cont)\ntest_set_rf_cont = scaler.transform(test_set_rf_cont)\ntest_set_rf_cont = pd.DataFrame(test_set_rf_cont, columns=cont_vars)\ntest_set_rf_cate = test_set_rf[cate_vars]\n\nscaled_test_set_rf = pd.concat([test_set_rf_cont, test_set_rf_cate], axis=1)\nscaled_test_set_rf.head()'}, {'role': 'assistant', 'content': 'data_preprocessing'}]