python统计字符串中字母出现的频次，以字典形式呈现。

Question

统计字符串中字母出现的频次，以字典形式呈现。
参考下面的例子，把空白处补充完整。

_______ ______   #导入re库函数

str1='''When I wrote the following pages, or rather the bulk of them, I lived alone, in the woods, a mile from any neighbor,  

in a house which I had built myself, on the shore of Walden Pond, in Concord, Massachusetts,  

and earned my living by the labor of my hands only.  

I lived there two years and two months. At preset I am a sojourner in civilized life again.'''

 

text=re.____(_____,_____,______)  #删除str1中的标点符号

dict1=_______    #定义一个空字典

for each in ______ :   #轮询text中的每个字符

   if each==' ' or each =='\n':   #如果是空格或者换行符，则忽略。

       continue

   elif each not in dict1.keys():

       ___________    

   else:

       ___________

print(dict1)

Answer 1

import re
str1='''When I wrote the following pages, or rather the bulk of them, I lived alone, in the woods, a mile from any neighbor,  
in a house which I had built myself, on the shore of Walden Pond, in Concord, Massachusetts,  
and earned my living by the labor of my hands only.  
I lived there two years and two months. At preset I am a sojourner in civilized life again.'''
text=re.sub('[.,]' ,' ',str1)  #删除str1中的标点符号
# print(text)
dict1= {}    #定义一个空字典
for each in text :   #轮询text中的每个字符
   if each==' ' or each =='\n':   #如果是空格或者换行符，则忽略。
       continue
   elif each not in dict1.keys():
       dict1[each] = 1
   else:
       dict1[each] += 1
print(dict1)