1 字典

特點

1.鍵-值成對出現 “鍵：值 ”

2.鍵不能重復

3.鍵不可更改，值可以修改

4.鍵來索引值

5.鍵只能是不可變的數據類型

dic_Python={'the define':1,'the age':2,'the clude':['A','B']
}
#增刪查改
dic_Python['the age']
dic_Python['the define']=77#賦值修改
dic_Python['hello']=50#賦值添加鍵值對
dic_Python.update({'hi':'world',})del dic_Python['the age']#刪除指定鍵值對dic_Python.keys()#訪問字典所有鍵
dic_Python.values()#訪問字典所有值
dic_Python.items()#訪問字典所有鍵值對third_dic={i:i**3 for i in range(1,11)}

2 統計單詞詞頻

常用方法

1.字符串.lower（）#將所有字母轉為小寫形式

2.字符串.split（）#將字符串拆分 返回列表，包含一系列單詞

?

sentence_1='Many flowers and trees have withered this night;Death will soon come and plant them over again.'
sentence_1.lower()
words=sentence_1.split()
word_num={}
for word in words:if word in word_num:word_num[word]+=1else:word_num[word]=1