[{'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:train_data3 = train_data2<br>train_data3["rooms_per_household"] = train_data3["total_rooms"]/train_data3["households"]<br>train_data3["bedrooms_per_room"] = train_data3["total_bedrooms"]/train_data3["total_rooms"]<br>train_data3["population_per_household"] = train_data3["population"]/train_data3["households"]<br>train_data3["income_per_person"] = train_data3["median_income"]/train_data3["population_per_household"]<br>train_data3[\'mean_rooms\'] = train_data3[\'total_rooms\']/train_data3[\'households\']<br>train_data3[\'rooms_per_person\'] = train_data3[\'total_rooms\']/train_data3[\'population\']<br>train_data3[\'mean_bedrooms\'] = train_data3[\'total_bedrooms\']/train_data3[\'households\']<br>train_data3[\'bedrooms_per_person\'] = train_data3[\'total_bedrooms\']/train_data3[\'households\']<br>train_data3[\'persons_per_household\'] = train_data3[\'population\']/train_data3[\'households\']<br>train_data3[\'total_income\'] = train_data3[\'median_income\']*train_data3[\'households\']'}, {'role': 'assistant', 'content': 'data_preprocessing'}]