Pandas中的UnboundLocalError

Question

我的任务是清理数据并以下一格式呈现：DataFrame（[[＆＃34; Michigan＆＃34;，＆＃34; Ann Arbor＆＃34;]，[＆＃34; Michigan＆＃34; ，＆＃34; Yipsilanti＆＃34;]]，columns = [＆＃34; State＆＃34;，＆＃34; RegionName＆＃34;]）。

我犯了一个错误。我该如何解决？ ＆＃34; UnboundLocalError：局部变量＆＃39; state＆＃39;在分配之前引用＆＃34;

代码如下：

 with open ('university_towns.txt') as file:
    data=[]
    for line in file:
        data.append(line[:-1])
state_town = []

for line in data:
    if line[:-6]=='[edit]':
        state=line[:-6]
    elif '(' in line:
        town = line[:line.index('(')-1]
        state_town.append([state,town])
    else:
        town=line
        state_town.append([state,town])
    state_college_df=pd.DataFrame(state_town, columns=['State','RegionName'])
return state_college_df