Python的数据类型5

数据类型5"/>

Python的数据类型5

一。字典dict的属性

1.字典的基本用法

info = {
“k1”:“v1”,#键值对，：代表赋值等于
“k2”:“v2”
}

2.字典的vlaue可以是任意类型

info = {"k1": 18,"k2": True,"k3": [11,[],(),22,33,{'kk1': 'vv1','kk2': 'vv2','kk3': (11, 22),}],"k4": (11, 22, 33, 44)
}
print(info)

3.布尔值，列表，字典不能作为字典的KEY

info = {1:'asdf',"k1":'qweqe',(123,11):122}
print(info)

4.字典是无序的*****************未尝试出来结果，等待修改

info = {"k1": 18,"k2": True,"k3": [11,[],(),22,33,{'kk1': 'vv1','kk2': 'vv2','kk3': (11, 22),}],"k4": (11, 22, 33, 44)
}
print(info)#多次输出发现其，随机出现顺序

5.利用索引查找列表中的元素（eg：11）

info = {"k1": 18,"k2": True,"k3": [11,[],(),22,33,{'kk1': 'vv1','kk2': 'vv2','kk3': (11, 22),}],"k4": (11, 22, 33, 44)
}
v = info["k3"][5]['kk3'][0]
print(v)

6.字典dict支持del删除

info = {"k1": 18,"k2": True,"k3": [11,[],(),22,33,{'kk1': 'vv1',#***'kk2': 'vv2','kk3': (11, 22),}],"k4": (11, 22, 33, 44)
}
del info['k1']#删除键值k1
print(info)
del info['k3'][5]['kk1']
print(info)

7.dic的for循环,默认循环字典的Key

info = {"k1": 18,2: True,"k3": [11,[],(),22,33,{'kk1': 'vv1',#***'kk2': 'vv2','kk3': (11, 22),}],"k4": (11, 22, 33, 44)
}
for item in info:#等于for item in info.keys()print(item)
for item1 in info.values():#输出dic中的valuesprint(item1)

注：循环输出dit中的键值对（key和values）：
方法一：自己循环输出

for item in info.keys():print(item,info[item])

方法二：使用.item()

for k, v in info.items():print(k,v)

二。字典dic的功能：
1.fromkeys（）根据序列，创建字典，指定统一的值

dic = {"k1":"v1"
}
v = dict.fromkeys(["k1",123,"999"],123)#123为values,"k1",123,"999"为dic的key
print(v)#生成字典类型，

2.get（）根据KEY获取字典中的值，如果KEY不存在默认为None（可以修改）

dic = {"k1":"v1"
}
v1 = dic.get('k1')
print(v1)
v2 = dic.get('k121')
print(v2)
v3 = dic.get('k121',11111)
print(v3)
v4 = dic.get('k1',11111)
print(v4)

3.pop(),删除并获取dic中的值,默认可以获取values（可以带参数，指定返回值）

dic = {"k1":"v1","k2":"v2"
}
v1 = dic.pop('k1')
print(dic,v1)v2 = dic.pop('k1',90)
print(dic,v2)v3 = dic.pop('k3',90)
print(dic,v3)

#popitem()删除并获取dic中的值,不可以带参数

dic = {"k1":"v1","k2":"v2"
}
v4 = dic.popitem()
print(dic,v4)k,v = dic.popitem()
print(dic,k,v)

4.设置dic中的数值，若已存在不设置并获取当前的key；若不存在，添加设置，并获取获取当前的key

dic = {"k1":"v1","k2":"v2"
}
v1 = dic.setdefault('k1',123)
print(dic,v1)
v2 = dic.setdefault('k1111',123)
print(dic,v2)

5.update更新，原来有就更新，没有则添加

dic = {"k1":"v1","k2":"v2"
}
dic.update({'k1':'1111','k3':123})#方法一
print(dic)
dic.update(k1=123,k3=324,k5="dasd")#方法二
print(dic)