[{'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:b"# brandtransforminverse_transformbrand\\nbrand_encoder = LabelEncoder().fit(device_brand[\'phone_brand\'])\\ndevice_brand[\'brand\'] = brand_encoder.transform(device_brand[\'phone_brand\'])\\nga_train[\'brand\'] = device_brand[\'brand\'] # device_iddevice_id\\nga_test[\'brand\'] = device_brand[\'brand\']\\n# devicetrainrow,brand1devicebrand\\nXtr_brand = csr_matrix((np.ones(ga_train.shape[0]), (ga_train[\'trainrow\'], ga_train[\'brand\'])))\\nXte_brand = csr_matrix((np.ones(ga_test.shape[0]), (ga_test[\'testrow\'], ga_test[\'brand\'])))\\nprint(Xtr_brand.shape, Xte_brand.shape)"'}, {'role': 'assistant', 'content': 'data_preprocessing'}]