技巧 | Python 字典用法详解(超全)
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2021-03-16 12:19
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字典(Dictionary)是Python提供的一种常用的数据结构,它用于存放具有映射关系的数据。本期给大家带来Python字典11个方法的全面解析,希望对你有所帮助。
字典由键(key)和值(value)成对组成,键和值中间以冒号:隔开,项之间用逗号隔开,整个字典由大括号 {} 括起来
格式如下:
dic = {key1 : value1, key2 : value2 }
# 方法1
dic1 = { 'Author' : 'Python当打之年' , 'age' : 99 , 'sex' : '男' }
# 方法2
lst = [('Author', 'Python当打之年'), ('age', 99), ('sex', '男')]
dic2 = dict(lst)
# 方法3
dic3 = dict( Author = 'Python当打之年', age = 99, sex = '男')
# 方法4
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', 99, '男']
dic4 = dict(zip(list1, list2))
字典创建的方式还有很多种,这里不再赘述。
接下来是重点
接下来是重点
接下来是重点
methods = dir(dict)
print('methods = ',methods)
methods = ['__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'clear', 'copy', 'fromkeys', 'get', 'items', 'keys', 'pop', 'popitem', 'setdefault', 'update', 'values']
字典的方法和属性有很多种,这里我们重点介绍以下 11 种方法:
['clear', 'copy', 'fromkeys', 'get', 'items', 'keys', 'pop', 'popitem', 'setdefault', 'update', 'values']
clear() 用于清空字典中所有元素(键-值对),对一个字典执行 clear() 方法之后,该字典就会变成一个空字典。
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', 99, '男']
dic1 = dict(zip(list1, list2))
# dic1 = {'Author': 'Python当打之年', 'age': 99, 'sex': '男'}
dic1.clear()
# dic1 = {}
2、dict.copy()
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', 99, '男']
dic1 = dict(zip(list1, list2))
dic2 = dic1 # 浅拷贝: 引用对象
dic3 = dic1.copy() # 浅拷贝:深拷贝父对象(一级目录),子对象(二级目录)不拷贝,还是引用
dic1['age'] = 18
# dic1 = {'Author': 'Python当打之年', 'age': 18, 'sex': '男'}
# dic2 = {'Author': 'Python当打之年', 'age': 18, 'sex': '男'}
# dic3 = {'Author': 'Python当打之年', 'age': 99, 'sex': '男'}
import copy
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
dic2 = dic1
dic3 = dic1.copy()
dic4 = copy.deepcopy(dic1)
dic1['age'].remove(18)
dic1['age'] = 20
# dic1 = {'Author': 'Python当打之年', 'age': 20, 'sex': '男'}
# dic2 = {'Author': 'Python当打之年', 'age': 20, 'sex': '男'}
# dic3 = {'Author': 'Python当打之年', 'age': [99], 'sex': '男'}
# dic4 = {'Author': 'Python当打之年', 'age': [18, 99], 'sex': '男'}
list1 = ['Author', 'age', 'sex']
dic1 = dict.fromkeys(list1)
dic2 = dict.fromkeys(list1, 'Python当打之年')
# dic1 = {'Author': None, 'age': None, 'sex': None}
# dic2 = {'Author': 'Python当打之年', 'age': 'Python当打之年', 'sex': 'Python当打之年'}
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
Author = dic1.get('Author')
# Author = Python当打之年
phone = dic1.get('phone')
# phone = None
phone = dic1.get('phone','12345678')
# phone = 12345678
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
items = dic1.items()
print('items = ', items)
print(type(items))
print('items = ', list(items))
# items = dict_items([('Author', 'Python当打之年'), ('age', [18, 99]), ('sex', '男')])
# <class 'dict_items'>
# items = [('Author', 'Python当打之年'), ('age', [18, 99]), ('sex', '男')]
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
keys = dic1.keys()
print('keys = ', keys)
print(type(keys))
print('keys = ', list(keys))
# keys = dict_keys(['Author', 'age', 'sex'])
# <class 'dict_keys'>
# keys = ['Author', 'age', 'sex']
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
sex = dic1.pop('sex')
print('sex = ', sex)
print('dic1 = ',dic1)
# sex = 男
# dic1 = {'Author': 'Python当打之年', 'age': [18, 99]}
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
dic1.popitem()
print('dic1 = ',dic1)
# dic1 = {'Author': 'Python当打之年', 'age': [18, 99]}
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
dic1.setdefault('Author', '当打之年')
print('dic1 = ',dic1)
# dic1 = {'Author': 'Python当打之年', 'age': [18, 99], 'sex': '男'}
dic1.setdefault('name', '当打之年')
print('dic1 = ',dic1)
# dic1 = {'Author': 'Python当打之年', 'age': [18, 99], 'sex': '男', 'name': '当打之年'}
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
print('dic1 = ',dic1)
# dic1 = {'Author': 'Python当打之年', 'age': [18, 99], 'sex': '男'}
list3 = ['Author', 'phone' ]
list4 = ['当打之年', 12345678]
dic2 = dict(zip(list3, list4))
print('dic2 = ',dic2)
# dic2 = {'Author': '当打之年', 'phone': 12345678}
dic1.update(dic2)
print('dic1 = ',dic1)
# dic1 = {'Author': '当打之年', 'age': [18, 99], 'sex': '男', 'phone': 12345678}
list1 = ['Author', 'age', 'sex']
list2 = ['Python当打之年', [18,99], '男']
dic1 = dict(zip(list1, list2))
values = dic1.values()
print('values = ', values)
print(type(values))
print('values = ', list(values))
# values = dict_values(['Python当打之年', [18, 99], '男'])
# <class 'dict_values'>
# values = ['Python当打之年', [18, 99], '男']
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