[{'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:#  feature  feature \n#  feature = ["temp","humidity","windspeed","atemp"]\n#  feature type category   . weather 1,2,3,4  2=>   . \n#  feature one-hot-encodding   .\ncategorical_feature_names = ["season","holiday","workingday","weather",\n                             "dayofweek","month","year","hour"]\n\nfor var in categorical_feature_names:\n    train[var] = train[var].astype("category")\n    test[var] = test[var].astype("category")\''}, {'role': 'assistant', 'content': 'data_preprocessing'}]