[{'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:def getProportion(df, feature):\ndef f(x):\nx = x.loc[:,[feature]].join(y_train, how='inner')\nreturn (x[x['event']==1]).count()/(x.count()+1)\ntemp = pd.DataFrame(x_train.groupby(feature).apply(f).iloc[:,0])\ntemp.columns = [feature+'SuccRate']\nreturn temp.merge(df, left_index=True,right_on=feature, how='inner')"}, {'role': 'assistant', 'content': 'data_preprocessing'}]