字典根据值找大小操作

person = {"li":18,"wang":50,"zhang":20,"sun":22}

#找到年龄最大的人
print(min(person,key=person.get))
#找到年龄最小的人
print(max(person,key=person.get))
#根据年龄排序
print(sorted(person,key=person.get))
print(sorted(person,key=person.get,reverse=True))

#运行结果
li
wang
['li', 'zhang', 'sun', 'wang']
['wang', 'sun', 'zhang', 'li']
Process finished with exit code 0

麻烦的方法：

person = {"li":18,"wang":50,"zhang":20,"sun":22}
a = person.values()
for key,val in person.items():
    if max(a) == val:   #可以改为min(a)
        print(key)

字典互换键值对：

person = {"li":18,"wang":50,"zhang":20,"sun":22}
#方法一
new_person = dict(zip(person.values(),person.keys()))
print(new_person)
#方法二
new_person = {}
for key,val in person.items():
    new_person[val] = key
print(new_person)
#方法三
new_person = dict([val,key] for key,val in person.items())
print(new_person)

{18: 'li', 50: 'wang', 20: 'zhang', 22: 'sun'}