[{'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_t=df_t.drop('Open Date',axis=1)\ndf_t['Type'].value_counts()\nty={'FC':0,'IL':1,'DT':2}\ndf_t['Type']=df_t['Type'].map(ty)\ncg={'Big Cities':0,'Other':1}\ndf_t['City Group']=df_t['City Group'].map(cg)\nx=0\nc={}\nfor i in df_t['City'].unique():\n    c.update({i:x})\n    x=x+1\ndf_t['City']=df_t['City'].map(c)"}, {'role': 'assistant', 'content': 'data_preprocessing'}]