[{'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:trn_image, vld_image, trn_label , vld_label = train_test_split(full_train_df['image'], \n                                               full_train_df['opacity'],\n                                               test_size=0.25,\n                                               random_state=2018)\ntrn_image = np.stack(trn_image, 0)\nvld_image = np.stack(vld_image, 0)"}, {'role': 'assistant', 'content': 'data_preprocessing'}]