详解python的字典及相关操作

student_A ={'name':'Allen','age':'14','grade':'8'} # 定义一个字典
print(student_A['name'])
print(student_A['age'])
print(student_A['grade'])

new_names = student_A['name']
new_ages = student_A ['age']
new_grades= student_A ['grade']
print("The student_A's name is " + new_names.title()+ ",and she is "+str(new_ages) +" years old,and Grade "+str(new_grades))

student_B={}
student_B['name']='Jack'
student_B['age']=13
student_B['grade']=7

student_A['address'] ="Hubei" #增加了一个地址健值对，由原来的3个变成4个
student_A['PhoneNumber'] ="18012345678"#增加了一个电话健值对，字典student_A里由4个变成5个
print(student_A)  #键 — 值对的排列顺序与添加顺序不同。Python不关心键-值对的添加顺序，而只关心键和值之间的关联关系

student_B['age']=14  #修改student_B的age值为14
print(student_B)
print("\n")

del student_A['address']
print(student_A)

favor_languages = {'jack': 'python','sarah': 'c','lucy': 'ruby','phil': 'python'}
print(favor_languages['lucy'])

for key,value in student_A.items():# 注意，student_A后增加了.items() 用于读取字典中的每一项
    print("\nKey: " + key)    #打印出关键字
    print("Value: " + value)  #打印出关键字的值
    
for name, language in favor_languages.items():     #遍历所有的键值对：用于遍历字典的for循环，可声明两个变量，用于存储键-值对中的键和值
    print(name.title() + "'s favorite language is " +language.title() + ".") #遍历字典中的每个键-值对，并将键存储在变量name中，而将值存储在变量language 中 
for name in favor_languages.keys():#遍历字典中的所有键，在不需要使用字典中的值时，方法 keys() ，注意后面增加的keys()
    print(name.title())  
print("\n")

my_friends = ['jack', 'sarah']
for name in favor_languages.keys():
    print(name.title())
        
    if name in my_friends: 
        print(" Hi " + name.title() +", I see your favorite language is " +favor_languages[name].title() + "!")

favor_languages= {'jack': 'python','polo': 'java','lucy': 'ruby','Albet': 'java'}
#使用函数 sorted() 来获得按特定顺序排列的键列表
for name in sorted(favor_languages.keys()): #对关键字进行排序
    print(name.title() + ", thank you !")
print("\n")     
#遍历字典中的所有值:如果主要获取的是字典包含的值，可使用方法 values()
for language in favor_languages.values():
    print(language.title())
print("\n")    
#使用集合（set）消除重复项  
for language in set(favor_languages.values()):
    print(language.title())