[Python Study Notes]字典操作

字典操作

a.增加

 >>> info["stu1104"] = "abc"
 >>> info
 {'stu1102': 'x5456', 'stu1104': 'abc', 'stu1103': 'Mali', 'stu1101': 'Wu'}

b.修改

 >>> info['stu1101'] = "xinge"
 >>> info
 {'stu1102': 'x5456', 'stu1103':  Mali', 'stu1101': 'xinge'}

c.删除

 >>> info
 {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1101': '武藤兰'}
 >>> info.pop("stu1101") #标准删除姿势
 '武藤兰'
 >>> info
 {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
 >>> del info['stu1103'] #换个姿势删除
 >>> info
 {'stu1102': 'LongZe Luola'}
 >>>
 >>>
 >>>
 >>> info = {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
 >>> info
 {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'} #随机删除
 >>> info.popitem()
 ('stu1102', 'LongZe Luola')
 >>> info
 {'stu1103': 'XiaoZe Maliya'}

d.查找

 >>> info = {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
 >>>
 >>> "stu1102" in info #标准用法
 True
 >>> info.get("stu1102")  #获取
 'LongZe Luola'
 >>> info["stu1102"] #同上，但是看下面
 'LongZe Luola'
 >>> info["stu1105"]  #如果一个key不存在，就报错，get不会，不存在只返回None
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
 KeyError: 'stu1105'

e.获取键值

 #values
 >>> info.values()
 dict_values(['LongZe Luola', 'XiaoZe Maliya'])

 #keys
 >>> info.keys()
 dict_keys(['stu1102', 'stu1103'])

f.合并

 #update
 >>> info
 {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1106': 'Alex'}
 >>> b = {1:2,3:4, "stu1102":"龙泽萝拉"}
 >>> info.update(b)
 >>> info
 {'stu1102': '龙泽萝拉', 1: 2, 3: 4, 'stu1103': 'XiaoZe Maliya', 'stu1106': 'Alex'}

g.深copy

 import copy
    
 n1 = {"k1": "wu", "k2": 123, "k3": ["alex", 456]}
    
 n4 = copy.deepcopy(n1)

h.循环

 #方法1
 for key in info:
     print(key,info[key])
  
 #方法2
 for k,v in info.items(): #会先把dict转成list,数据里大时莫用
     print(k,v)