import os os.chdir('C:\Python33\HeadFirstPython\hfpy_code\chapter5')   #将工作空间修改为文件所在的目录 #定义函数get_filedata从文件中取值 def get_filedata(filename):     try:         with open(filename)  as f:            #with语句打开和自动关闭文件             data=f.readline()                 #从文件中逐行读取字符             return (data.strip().split(','))  #将字符间的空格清除后，用逗号分隔字符     except IOError as ioerr:         print ('File Error' + str(ioerr))     #异常处理，打印错误         return (None) #定义函数modify_time_format将所有文件中的时分表达方式统一为“分.秒” def modify_time_format(time_string):     if "-" in time_string:         splitter="-"     elif ":" in time_string:         splitter=":"     else:         splitter="."     (mins, secs)=time_string.split(splitter)  #用分隔符splitter分隔字符后分别存入mins和secs     return (mins+ '.' +secs) #定义函数get_prev_three返回文件中排名前三的不重复的时间成绩 def get_prev_three(filename):     new_list=[modify_time_format(each_t) for each_t in get_filedata(filename)]   #采用列表推导将统一时分表达方式后的记录生成新的列表     delete_repetition=set(new_list)                                              #采用集合set函数删除新列表中重复项，并生成新的集合     in_order=sorted(delete_repetition)                                           #采用复制排序sorted函数对无重复性的新集合进行排序     return (in_order[0:3])                                                       #返回列表前三项 # 分别输出对应文件中排名前三的不重复的时间成绩 print (get_prev_three("james.txt")) print (get_prev_three("julie.txt")) print (get_prev_three("mikey.txt")) print (get_prev_three("sarah.txt"))

['2.01', '2.22', '2.34'] ['2.11', '2.23', '2.59'] ['2.22', '2.38', '2.49'] ['2.18', '2.25', '2.39']