python基础之字典、赋值补充

 字典常用操作：

 　　　　存/取
info_dic={'name':'egon','age':18,'sex':'male'}
 print(info_dic['name11111111'])
 print(info_dic.get('name',None))

pop：key存在则弹出值，不存在则返回默认值，如果没有默认值则报错
 print(info_dic.pop('nam123123123123123123e',None))
 print(info_dic)
print(info_dic.popitem())
 print(info_dic)
info_dic['level']=10
 print(info_dic)
　　　　删除
 info_dic={'name':'egon','age':18,'sex':'male'}
 info_dic.pop()
info_dic.popitem()
 del info_dic['name']
　　　　键s，值s，键值对
 info_dic={'name':'egon','age':18,'sex':'male'}
 print(info_dic.keys())
 print(info_dic.values())
 print(info_dic.items())

 for k in info_dic:
     print(k,info_dic[k])
     print(k)

 print('===>')
 for k in info_dic.keys():
     print(k)

 for val in info_dic.values():
     print(val)

 for k,v in info_dic.items(): #k,v=('name', 'egon')
     print(k,v)



　　　　长度
 info_dic={'name':'egon','age':18,'sex':'male'}
  print(len(info_dic))


 　　　　包含in

 info_dic={'name':'egon','age':18,'sex':'male'}
 print('name' in info_dic)
 print('name' in info_dic.keys())
 print('egon' in info_dic.values())
 print(('name','egon') in info_dic.items())

掌握

 info_dic={'name':'egon','age':18,'sex':'male'}
 info_dic.update({'a':1,'name':'Egon'})
 print(info_dic)

 info_dic['hobbies']=[]
 info_dic['hobbies'].append('study')
 info_dic['hobbies'].append('read')
 print(info_dic)

setdefault:key不存在则设置默认值，并且放回值默认值
key存在则不设置默认，并且返回已经有的值

 info_dic.setdefault('hobbies',[1,2])
 print(info_dic)
 info_dic={'name':'egon','age':18,'sex':'male'}
  info_dic.setdefault('hobbies',[1,2,3,4,5])
 info_dic.setdefault('hobbies',[1,2,]).append('study')
 print(info_dic)

 info_dic={'name':'egon','age':18,'sex':'male'}

 {'name':'egon','age':18,'sex':'male','hobbies':['study']}
 info_dic.setdefault('hobbies',[]).append('study')

 {'name':'egon','age':18,'sex':'male','hobbies':['study','read']}
 info_dic.setdefault('hobbies',[]).append('read')

 {'name':'egon','age':18,'sex':'male','hobbies':['study','read','sleep']}
 info_dic.setdefault('hobbies',[]).append('sleep')
 l=info_dic.setdefault('hobbies',[])
 print(l,id(l))
 print(id(info_dic['hobbies']))

 print(info_dic)

赋值补充

x=10

链式赋值
a=b=c=d=e=f=10
print(a,b,c,d,e,f)

增量赋值

x=10
y='a'
temp=x
x=y
y=temp
print(x,y)


x,y=y,x
print(x,y)

值的解压
msg='hello'
l=[1,2,3]

a,b,c,d,e=msg
print(a,b,c,d,e)

a,_,_,_,e=msg
a,*_,e=msg
print(a)
print(e)



dic={'a':1,'b':2,'c':3}
x,y,z=dic
print(x,y,z)