python的数据类型

Posted 2020-08-15

基本数据类型：

>>数和字符串

列表：

>>python中没有数组的概念，与数组最接近的概念是列表和元祖，列表是存储一连串元素的容器

>>> str = [‘ab‘,‘cd‘,‘ef‘,‘g‘]
>>> print(str[3])
g

>>修改列表中的内容

 

>>> str = [‘ab‘,‘cd‘,‘ef‘,‘g‘]
>>> str[3] = ‘gh‘
>>> print (str)
[‘ab‘, ‘cd‘, ‘ef‘, ‘gh‘]

 

元祖：python中没有数组的概念，与数组最接近的概念是列表和元祖，元祖是存储一连串元素的容器

 

>>> str = (‘ab‘,‘cd‘,‘ef‘,‘g‘)
>>> print(str[1])
cd

 

>>只读取不能修改

>>> str = (‘ab‘,‘cd‘,‘ef‘,‘g‘)
>>> abc = str[2]
>>> print(abc)
ef
>>> str[0] = ‘a‘
Traceback (most recent call last):
  File "<pyshell#13>", line 1, in <module>
    str[0] = ‘a‘
TypeError: ‘tuple‘ object does not support item assignment

 

集合：

>>python中集合主要有两个功能：

　>>建立关系

>>> a = set(‘abcdef‘)
>>> b = set(‘abc‘)
>>> x = a&b　　#交集
>>> print(x)
{‘c‘, ‘a‘, ‘b‘}
>>> y = a|b　　#并集
>>> print(y)
{‘b‘, ‘e‘, ‘f‘, ‘c‘, ‘a‘, ‘d‘}
>>> z = a-b　　#差集
>>> print(z)
{‘f‘, ‘d‘, ‘e‘}

 

　>>消除重复元素

>>> a = (‘abcdabcabc‘)
>>> new = set(a)
>>> print(new)
{‘c‘, ‘b‘, ‘a‘, ‘d‘}

 

字典：

也叫作关联数组，在{}以键值对的形式存储

>>> dic = {‘name‘:‘xiaoxiao‘,‘age‘:1,‘city‘:‘beijing‘}
>>> print(dic)
{‘age‘: 1, ‘city‘: ‘beijing‘, ‘name‘: ‘xiaoxiao‘}
>>> print(dic[‘name‘])
xiaoxiao

>>添加修改字典

>>> dic = {‘name‘:‘xiaoxiao‘,‘age‘:1}
>>> print(dic)
{‘age‘: 1, ‘name‘: ‘xiaoxiao‘}
>>> dic[‘city‘] = ‘beijing‘
>>> print(dic)
{‘age‘: 1, ‘city‘: ‘beijing‘, ‘name‘: ‘xiaoxiao‘}
>>> dic[‘age‘] = 0
>>> print(dic)
{‘age‘: 0, ‘city‘: ‘beijing‘, ‘name‘: ‘xiaoxiao‘}