[{'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:m = phone.phone_brand.str.cat(phone.device_model)\nmodelencoder = LabelEncoder().fit(m)\nphone['model'] = modelencoder.transform(m)\ngatrain['model'] = phone['model']\ngatest['model'] = phone['model']\nXtr_model = csr_matrix((np.ones(gatrain.shape[0]), \n                       (gatrain.trainrow, gatrain.model)))\nXte_model = csr_matrix((np.ones(gatest.shape[0]), \n                       (gatest.testrow, gatest.model)))\nprint('Model features: train shape {}, test shape {}'.format(Xtr_model.shape, Xte_model.shape))"}, {'role': 'assistant', 'content': 'data_preprocessing'}]