python 字典

1 dic = {'name':'tom'}
2 dic['age'] = 18
3 print(dic)

1 dic = {'name':'tom'}
2 dic['name'] = 18
3 print(dic)

1 dic = {'name':'tom'}
2 dic['age'] = 18
3 print(dic)
4 
5 # 键存在则不进行操作，并把原有的值作为返回值;键不存在，则增加
6 dic.setdefault('age', '34')  
7 
8 print(dic)

1 dic = {'name':'tom', 'age':'22', 'hobby':'ss'}
2 print(dic.keys())   #输出字典的键
3 print(list(dic.keys()))   #以列表的形式输出字典的键
4 print(list(dic.values())) #以列表形式输出字典键所对应的值

1 dic1 = {'name':'tom', 'age':'22', 'hobby':'ss'}
2 dic2 = {'name':'tom', 'age':'12', 'hobby':'小可爱'}
3 print(dic1)
4 dic1.update(dic2)  #把dic2的内容更新到dic1中
5 print(dic1)

 1 dic1 = {'name':'tom', 'age':'12', 'hobby':'小可爱'}
 2 dic2 = {'name':'tom', 'age':'12', 'hobby':'小可爱'}
 3 del dic1['name']    #删除指定键值对
 4 print(dic1)
 5 
 6 ret = dic1.pop('age')    #删除指定键值对，并返回键值所对应的值
 7 print(ret)
 8 print(dic1)
 9 
10 a = dic2.popitem()    #随机删除某个键值对，并以元组方式返回
11 print(a,dic2)

1 dic = {'name':'tom', 'age':'12', 'hobby':'小可爱'}
2 dic.clear()   #清空字典
3 print(dic)
4 
5 del dic   # 删除整个字典

 1 dic_nate = {
 2     "欧美":{
 3         "www.123.com":["质量一般","免费"],
 4         "www.234.com":["质量一般","高清"],
 5         "www.345.com":["质量优","收费，屌丝绕路"]
 6     },
 7     "日韩":{
 8         "www.456.com":["质量优","免费"]
 9     },
10     "大陆":{
11         "www.567.com":["质量差","网速慢"]
12     }
13 }
14 
15 dic_nate['欧美']["www.234.com"][1] = '垃圾'  # 修改键值
16 print(dic_nate)

1 dic = {'name':'tom', 'age':'12', 'hobby':'小可爱'}
2 
3 for n in dic:
4     print(n) #输出键
5     print(n, dic[n]) #输出键和键值

1 dic = {'name':'tom', 'age':'12', 'hobby':'小可爱'}
2 
3 for n,m in dic.items():  #用两个变量分别接收键和键值
4     print(n, m)

1 a = eval(a)    #转换成字典类型