[{'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.drop(['Date','Customers','Open','PromoInterval','monthStr'],axis=1,inplace =True)\ntest.drop(['Date','Open','PromoInterval','monthStr'],axis=1,inplace =True)\n\n\n# train = train[train.Sales != 0]\n\nho_xtrain = train.drop(['Sales'],axis=1 )\nho_ytrain = train.Sales\n\nho_xtest=test\nho_xtest=ho_xtest.sort_values(by=['Id'])\n# ho_xtest = test.drop(['Sales'],axis=1 )\n# ho_ytest = test.Sales"}, {'role': 'assistant', 'content': 'data_preprocessing'}]