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python 基础知识4 - 字典

时间:2020-05-05 19:32:32      阅读:69      评论:0      收藏:0      [点我收藏+]

1、字典增

#字典增
dic = {name: 大白, age: 20}
dic[hight] = 180  #没有键值对,添加
dic[age] = 18   #有键值对,覆盖
print(dic)
#{‘name‘: ‘大白‘, ‘age‘: 20, ‘hight‘: 180}
#{‘name‘: ‘大白‘, ‘age‘: 18

#setdefault
dic = {name: 大白, age: 20}
dic.setdefault(weight,150)# 没有height此键,则添加
print(dic)#{‘name‘: ‘大白‘, ‘age‘: 20, ‘weight‘: 150}
dic.setdefault(name,150)# 有此键则不变
print(dic)#{‘name‘: ‘大白‘, ‘age‘: 20}

2、字典删

dic = {name: 大白, age: 20}
print(dic.pop(age))#20(有返回值)
print(dic.pop(hight,没有此键))#没有此键
print(dic)#{‘name‘: ‘大白‘}


#popitem 3.5版本之前,popitem为随机删除,3.6之后为删除最后一个,有返回值
dic = {name: 大白, age: 20}
dic.popitem()
print(dic)#{‘name‘: ‘大白‘}


#clear 清空字典
dic = {name: 大白, age: 20}
dic.clear()
print(dic) # {}

# del
# 通过键删除键值对
dic = {name: 大白, age: 20}
del dic[name]
print(dic) # {‘age‘: 20}
#删除整个字典
del dic

 

 3、字典改

#update
dic1 = {name:jin,age:18,sex:mal}
dic2 = {name:alex,weight:75}
dic1.update(dic2)#将2更新到1里
print(dic1) # {‘name‘: ‘alex‘, ‘age‘: 18, ‘sex‘: ‘male‘, ‘weight‘: 75}
print(dic2) # {‘name‘: ‘alex‘, ‘weight‘: 75}

 4、字典查

#keys()查键
dic = {name: 大白, age: 20}
print(dic.keys()) # dict_keys([‘name‘, ‘age‘])

#values()查键值
dic = {name: 大白, age: 20}
print(dic.values()) #dict_values([‘大白‘, 20])

#items()查键值对
dic = {name: 大白, age: 20}
print(dic.items()) #dict_items([(‘name‘, ‘大白‘), (‘age‘, 20)])

for i in dic.items():
    print(i)
# (‘name‘, ‘大白‘)
# (‘age‘, 20)

for i,j in dic.items():
print(i,j)
# name 大白
# age 20
#get
dic = {name: 大白, age: 20}
print(dic.get(age))#20
print(dic.get(hight))#(若无)None

 

 
 

 

 4、dict嵌套

 

dic = {name:[大白,python,小白],
        py9: {num: 71, age: 18},
        True: 1,
        (1, 2, 3): 123,
        2: 白鸽, }
dic[name][1]=dic[name][1].upper()#将‘name‘中‘python‘大写
dic[py9][female] = 6#将‘female‘:6添加到‘py9‘中
print(dic)

 

python 基础知识4 - 字典

原文:https://www.cnblogs.com/2584808136-qq-com/p/12831757.html

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