[{'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   .\nprint(train.shape)\n\n# "     "  .\ntrain["datetime-year"] = train["datetime"].dt.year\ntrain["datetime-month"] = train["datetime"].dt.month\ntrain["datetime-day"] = train["datetime"].dt.day\ntrain["datetime-hour"] = train["datetime"].dt.hour\ntrain["datetime-minute"] = train["datetime"].dt.minute\ntrain["datetime-second"] = train["datetime"].dt.second\n\n# 20180124 \ntrain["datetime-dayofweek"] = train["datetime"].dt.dayofweek\n\n#    train   .\nprint(train.shape)\n\n\n#    .\ntrain[["datetime", "datetime-year", "datetime-month", "datetime-day",\n       "datetime-hour", "datetime-minute", "datetime-second", "datetime-dayofweek"]].head()\''}, {'role': 'assistant', 'content': 'data_preprocessing'}]