[{'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:df_90_00 = pd.merge(df_exp_1990,df_exp_2000,on=\'Country\',suffixes=(\'_1990\',\'\'))\ndf_90_15 = pd.merge(df_90_00,df_exp_2015,on=\'Country\',suffixes=(\'_2000\',\'_2015\'))\ndf_90_15.drop([\'Year_1990\',\'Year_2000\',\'Year_2015\',\'Country\'], axis=1, inplace=True)\ndf_90_15.drop([\'IWPct_1990\',\'IWPct_2000\',\'IWPct_2015\'], axis=1, inplace=True)\ndf_90_15.drop([\'ISPct_1990\',\'ISPct_2000\',\'ISPct_2015\'], axis=1, inplace=True)\ndf_90_15 = df_90_15[sorted(df_90_15.columns)]\ndf_90_15.plot(kind=\'box\',figsize=(10,10),ylim=(-10,110),rot=30)\npyplot.title("Changes in access over time")\npyplot.ylabel("Pct with access")\npyplot.xlabel("1990-2015")'}, {'role': 'assistant', 'content': 'data_exploration'}]