Python--字典操作

字典的增删改查及遍历

info = {
    "stu3":"yuanyuan",
    "stu1":"tianjie",
    "stu2":"wangxinlin"
}
print(type(info)) #输出类型
print(info)
print(info["stu1"]) #查找 条件：适用于确定有该键值,没有键值时报错
print(info.get("stu00")) #没有时返回None
print(info.get("stu1")) #有就返回value

print("stu02" in info) #判断是否存在该数据，如果存在返回True，不存在返回False
# info.has_key("stu1") # 适用于py2

info["stu2"] = "fenglubei"  #修改
print(info)
info["stu4"] = "wangxinlin" #没有该键时新增
print(info)

del info["stu1"] #删除
print(info)

info.pop("stu2") #删除特定键值
print(info)

info.popitem() #随机删
print(info)

#字典嵌套
shuqike = {
    "gongsi":{
        "kaifa":["ma","jiaming","jiao","yuan","yaqiong","zhendong"],
        "yunwei":["yecai","majin"]
    },
    "SJS":{
        "kaifa":["cong","jiang"],
        "yunwei":["feng","tian","xinlin","yuanyuan"]
    }
}
print(shuqike)

#查
print(shuqike["gongsi"]["kaifa"][2])
print(shuqike["SJS"]["yunwei"][2])

#改
shuqike["gongsi"]["kaifa"][2] = "zhen"
print(shuqike)

#增加
shuqike["gongsi"]["jiagou"] = ["hou","peng"]
print(shuqike)

#高级
zimu = {
    "大写":["A","B","C"],
    "小写":["a","b","c"]
}
print(zimu.keys()) #获取列表里的所有key
print(zimu.values()) #获取列表里的所有value

# setdefault,在字典里取值，当能取到值时就不动字典，当取不到值时，创建一个
zimu.setdefault("qita", [1,2,3])
zimu.setdefault("大写", ["D"])
print(zimu)

#update,存在交叉，更新值，不存在键则新增
b = {
    "小写":"fff",
    1:2,
    3:4
}
zimu.update(b)
print(zimu)

print(zimu.items()) #字典转列表

c = dict.fromkeys([6,7,8],"test") #创建一个字典，key为678，值都为test
print(c)

d = dict.fromkeys([1,2,3],[1,{"name":"tinajie"},333])
print(d)
d[3][1]["name"] = "yuanyuan"  #都改，并不是只改一个
print(d)

#字典的遍历
for i in zimu:
    print(i) #只打印key
    print(i,zimu[i])

for k,v in zimu.items():  #效率低于上面那种，因为要转成列表
    print(k,v)