[{'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:people_df = pd.read_csv('../input/people.csv')\ncolumns = ['char_'+str(i) for i in range(1,10)]\npeople_df[columns] = people_df[columns].apply(lambda x: x.astype('category').cat.codes)\npeople_df['group_1'] = people_df['group_1'].astype('category').cat.codes\npeople_df['date'] = pd.to_datetime(people_df['date'])\npeople_df['day'] = people_df['date'].apply(lambda x:x.day)\npeople_df['year'] = people_df['date'].apply(lambda x:x.year)\npeople_df['month'] = people_df['date'].apply(lambda x:x.month)\npeople_df = people_df.drop(['date'],axis = 1)\npeople_df = people_df.set_index(people_df['people_id'])\npeople_df.head()"}, {'role': 'assistant', 'content': 'data_preprocessing'}]