英文词频统计预备，组合数据类型练习

1. 实例: 下载一首英文的歌词或文章，将所有,.？！等替换为空格，将所有大写转换为小写，统计某几个单词出现的次数，分隔出一个一个的单词。

   a = '''God Is A Girl
   Remembering me, 
   Discover and see 
   All over the world, 
   She's known as a girl 
   To those who a free, 
   The mind shall be key 
   Forgotten as the past 
   'Cause history will last 
   God is a girl, 
   Wherever you are, 
   Do you believe it, can you recieve it? 
   God is a girl, 
   Whatever you say, 
   Do you believe it, can you recieve it? 
   God is a girl, 
   However you live, 
   Do you believe it, can you recieve it? 
   God is a girl, 
   She's only a girl, 
   Do you believe it, can you recieve it? 
   She wants to shine, 
   Forever in time, 
   She is so driven, she's always mine 
   Cleanly and free, 
   She wants you to be 
   A part of the future, 
   A girl like me 
   There is a sky, 
   Illuminating us, someone is out there 
   That we truly trust 
   There is a rainbow for you and me 
   A beautiful sunrise ete'''
   a =a.lower()
   print('god出现次数为：'+str(a.count('god')))
   for i in ',','?','!':
       a=a.replace(i,' ')
   a=a.split(' ')
   print(a)

    

    

2. 列表实例：由字符串创建一个作业评分列表，做增删改查询统计遍历操作。例如，查询第一个3分的下标，统计1分的同学有多少个，3分的同学有多少个等。

   grade=list('12312133212321')
   grade=[int(x) for x in grade]
   print('成绩表：',grade)
   
   grade.insert(0,2)
   print('开始增加分值为2的分数',grade)
   grade.pop(0)
   print('删除增加的分数',grade)
   print('输出第一个3分的同学的下标:',grade.index(3))
   print('统计1分的同学人数:',grade.count(1))
   
   print('统计3分的同学人数:',grade.count(3))

   

    

3. 简要描述列表与元组的异同。                                                                           
4. 列表是可变的数据类型，用方括号显示。元组是不可变的 ，用圆括号显示。两者都可以嵌套。