[{'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:users = movieratings.ix[:,0].values\nsongs = movieratings.ix[:,1].values\nratings = movieratings.ix[:,2].values\nuni_users = movieratings['userId'].unique()\nuni_songs = movieratings['movieId'].unique()\nuser_map = dict(zip(uni_users,range(len(uni_users))))\nsong_map = dict(zip(uni_songs,range(len(uni_songs))))\nuser_idx =  np.array([ user_map[user] for user in users])\nsong_idx =  np.array([ song_map[song] for song in songs])\nprint(len(uni_users),len(uni_songs))"}, {'role': 'assistant', 'content': 'data_preprocessing'}]