1、数据类型的划分
数据类型分为:可变数据类型,不可变数据类型
-
- 不可变数据类型:元祖、bool、int、str 可哈希
- 可变数据类型:list,dic,set 不可哈希
2、dic的数据结构
dic key:必须为可哈希数据类型,不可以变数据类型
value:任意数据类型
dic 优点:二分查找,存储大量关系型数据
dic特点:3.6以前无序,3.6后有序
3、dic的增、删、改、查
定义
dic = { ‘name‘: [‘bear‘, ‘Honey‘, ‘bee‘], ‘myPthon‘: [{‘num1‘: 71, ‘avg_age‘: 18} ,{‘num1‘: 71, ‘avg_age‘: 18} ,{‘num1‘: 71, ‘avg_age‘: 18}], True: 1, (1, 2, 3): ‘bee‘, 2: ‘Honey‘ } print(dic)
The key value is an immutable type(hash),which can be tuple,bool,int,str. (immutable:不可变)
But when the key value is a tuple, it must be an immutable type.
A varable tuple like this is not posible:(1, 2, 3, [1, 2]).
It will reopot errors:TypeError: unhashable type: ‘list‘.
增
dic1 = {‘age‘: 18, ‘name‘: ‘bear‘, ‘sex‘: ‘male‘} dic2 = {} # if the key value does not exist to be added to the dictionary dic1[‘high‘] = 185 # if the dictionary has a key value, update the corresponding value to the dictionary (corresponding:相符的) dic1[‘age‘] = 15 # Key value does not exist, default add none to dictionary dic1.setdefault(‘weight‘) # The key value does note exist, if the second parameter is specified,add the (key,value) pair to the dictionary dic1.setdefault(‘weight‘, 90) # If the key value already exists,the specified value will not be update to the dictionary dic1.setdefault(‘name‘, ‘bee‘)
删
改
查
原文地址:https://www.cnblogs.com/zxw-xxcsl/p/11478580.html
时间: 2024-09-29 04:04:52