[{'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:X_val_A = val_prediction[: int(len(val_prediction)/2)]\nX_val_B = val_prediction[int(len(val_prediction)/2) :]\nX_train_neither = np.concatenate((X_val_A, X_val_B), axis=1)\n\nY_val_A = Y_validation[: int(len(Y_validation)/2)]\nY_val_B = Y_validation[int(len(Y_validation)/2) :]\nY_train_neither = 1 - Y_val_A - Y_val_B'}, {'role': 'assistant', 'content': 'data_preprocessing'}]