Python 字典
- 字典是另一种可变容器模型，且可存储任意类型对象。
- 字典的每个键值 key=>value 对用冒号 : 分割，每个键值对之间用逗号 , 分割，整个字典包括在花括号 {} 中 ,格式如下所示：
d = {key1 : value1, key2 : value2
- 键必须是唯一的，但值则不必。
- 值可以取任何数据类型，但键必须是不可变的，如字符串，数字或元组。
-
dic = {'name':'jin','age':18,'sex':'male'} print(dic)#{'name': 'jin', 'sex': 'male', 'age': 18}####增####
-
#增 ##第一种:有则覆盖，无则添加 # dic = {'name':'jin','age':18,'sex':'male'} # dic['hobby'] = 'girl' # print(dic) #输出{'age': 18, 'hobby': 'girl', 'sex': 'male', 'name': 'jin'} # dic['name'] = 'wusir' # print(dic) #{'age': 18, 'sex': 'male', 'name': 'wusir'} # ##第二种:serdefult 无则添加,有则不变 dic = {'name':'jin','age':18,'sex':'male'} # dic.setdefault('hobby') # print(dic)#{'sex': 'male', 'hobby': None, 'age': 18, 'name': 'jin'} #'hobby'是键，而不是值，所以字典里会出现'hobby':None # dic.setdefault('hobby','girl') # print(dic)#{'name': 'jin', 'hobby': 'girl', 'age': 18, 'sex': 'male'} #键值对 'hobby':girl添加到字典了、原字典没有hobby # dic.setdefault('name','ritian') # print(dic)#{'age': 18, 'name': 'jin', 'sex': 'male'} #原字典中有k,name'所以不变###删####
-
#pop 有返回值 # dic = {'name':'jin','age':18,'sex':'male'} # print(dic.pop('age'))##返回所删除键值对的age值18 # print(dic) # dic.pop('hobby')##报错 # print(dic.pop('hobby',None))##设定返回的键值，当hobby不存在时，返回None ##clear 清空 # dic = {'name':'jin','age':18,'sex':'male'} # dic.clear() # print(dic)#{}清空字典里面所有键值对 ##del # dic = {'name':'jin','age':18,'sex':'male'} # del dic # print(dic)#NameError: name 'dic' is not defined,通过del dic,已删除字典dic # dic = {'name':'jin','age':18,'sex':'male'} # del dic['name'] # print(dic)#{'age': 18, 'sex': 'male'},删除dic里面‘name’的键值对 # dic = {'name':'jin','age':18,'sex':'male'} # print(dic.popitem()) # print(dic)#每次随机删除dic里面的键值对####改#####
-
# dic = {"name":"jin","age":18,"sex":"male"} # dic['name'] = '太白' # print(dic)#{'name': '太白', 'sex': 'male', 'age': 18}更改键name的值 # 两个字典的改 # dic = {"name":"jin","age":18,"sex":"male"} # dic2 = {"name":"alex","weight":75} # dic2.update(dic)#将dic键值对，覆盖并添加到dic2 # print(dic)#{'age': 18, 'name': 'jin', 'sex': 'male'} # print(dic2)#{'age': 18, 'sex': 'male', 'name': 'jin', 'weight': 75}####查####
# dic = {"name":"jin","age":18,"sex":"male"}
# print(dic['name'])#jin 查键所对应的值jin
# print(dic['name1'])#KeyError: 'name1'如果查看没有的键，则会显示错误信息
# print(dic.get('name'))#jin
# print(dic.get('name1'))#没有此键时默认返回None
# print(dic.get('name1','无此键值对'))#无此键值对,后面可以设置···
##其它方法
#key() values() item()
dic = {"name":"jin","age":18,"sex":"male"}
# print(dic.keys(),type(dic.keys()))#查看dic的键keys
# print(dic.keys())#
# for i in dic.keys():
# print(i)
#列出dic的所有键
# for i in dic:
# print(i)
# li = list(dic.keys())#以列表的形式查看dic键
# print(li)
# print(dic.values())#值
# for i in dic.values():#列出dic的键值
# print(i)
#
#items 随机打出dic的键值对
# print(dic.items())#打出dic的键值对，顺序随机
#dict_items([('age', 18), ('sex', 'male'), ('name', 'jin')])
# for i in dic.items():#
# print(i,type(i))
# ('name', 'jin') <class 'tuple'>
# ('sex', 'male') <class 'tuple'>
# ('age', 18) <class 'tuple'>
原文地址：http://blog.51cto.com/dongw/2089999
时间： 2024-11-05 11:24:04