python-字典

# 创建字典的几种方式：

# 方式1:
dic = dict(((‘one‘, 1),(‘two‘, 2),(‘three‘, 3)))
print(dic)  # {‘one‘: 1, ‘two‘: 2, ‘three‘: 3}


# 方式2:
dic = dict(one=1,two=2,three=3)
print(dic)  # {‘one‘: 1, ‘two‘: 2, ‘three‘: 3}


# 方式3:
dic = dict({‘one‘: 1, ‘two‘: 2, ‘three‘: 3})
print(dic)  # {‘one‘: 1, ‘two‘: 2, ‘three‘: 3}

增
dic = {‘name‘:‘小超银‘,‘age‘:‘18‘}
#直接增加
#若增加的已有的键，则覆盖。无则加
# dic[‘sex‘]=‘男‘
# print(dic)   #{‘sex‘: ‘男‘, ‘age‘: ‘18‘, ‘name‘: ‘小超银‘}
# dic[‘age‘] = 23
# print(dic)    # {‘name‘: ‘小超银‘, ‘age‘: 23}

# setdefault
# 若增加的已有的键，则不改变
# dic.setdefault(‘hobby‘,‘篮球‘)
# print(dic)
dic.setdefault(‘age‘,‘45‘)
print(dic)    # {‘age‘: ‘18‘, ‘name‘: ‘小超银‘}

删

#pop 按照键删除键值对
# 如果设置第二个参数，无论字典里有无此键都不会报错
dic = {‘name‘:‘小超银‘,‘age‘:‘18‘}
dic.pop(‘age‘)
print(dic)      #{‘name‘: ‘小超银‘}
ret = dic.pop(‘hobby‘,‘没有此键‘)
print(ret)       # 没有此键

#clear 清空字典内的内容
dic.clear()
print(dic)       # {}

#del
del dic[‘age‘]
print(dic)        #{‘name‘: ‘小超银‘}

改

#直接改
dic = {‘name‘:‘小超银‘,‘age‘:‘18‘}
dic[‘name‘] =‘无所不能的小超银‘
print(dic)    #{‘age‘: ‘18‘, ‘name‘

#查

#直接查
dic = {‘name‘:‘小超银‘,‘age‘:‘18‘,‘hobby‘:[‘篮球‘,‘lol‘,‘吃鸡‘]}
print(dic[‘hobby‘])   # [‘篮球‘, ‘lol‘, ‘吃鸡‘]
print(dic[‘hobby1‘])  # 报错

#get
dic = {‘name‘:‘小超银‘,‘age‘:‘18‘,‘hobby‘:[‘篮球‘,‘lol‘,‘吃鸡‘]}
l =dic.get(‘hobby‘)
print(l)   #[‘篮球‘, ‘lol‘, ‘吃鸡‘]
l1 =dic.get(‘hobby1‘)
print(l1)  #None
l2 =dic.get(‘hobby1‘,‘没有此键‘)
print(l2)  #没有此键

python-字典

原文：https://www.cnblogs.com/xiaochaoyin/p/12907636.html