Python学习笔记第七天

每日一句：All things in their being are good for something.

遍历字典

字典用于以各种形式存储信息

1.遍历所有的键-值对

user_0={
    'username':'efermi',
    'first':'enrico',
    'last':'fermi',
}
for key,value in user_0.items():
    print("\nKey:"+key)
    print("Value:"+value)
# for k,v in 字典.items():
# k,v分别用来存储字典的键和值

Key:username
Value:efermi

Key:first
Value:enrico

Key:last
Value:fermi

favorite_languages={
    'jen':'python',
    'sarah':'c',
    'edward':'rudy',
    'phil':'java'
}
for name,language in favorite_languages.items():
    print(name.title()+"'s favorite language is "+language.title()+".")
items()表示字典中所有的键-值

Jen's favorite language is Python.
Sarah's favorite language is C.
Edward's favorite language is Rudy.
Phil's favorite language is Java.

favorite_languages={
    'jen':'python',
    'sarah':'c',
    'edward':'rudy',
    'phil':'java'
}
for name in favorite_languages.keys():
    print(name.title())
# for name in favorite_languages:
#     print(name.title())
# 与上面代码结果一样，上面代码更容易理解
# keys()表示字典中所有的键
print("------------")
for language in favorite_languages.values():
    print(language)
# keys()表示字典中所有的值

Jen
Sarah
Edward
Phil
------------
python
c
rudy
java

favorite_languages={
    'jen':'python',
    'sarah':'c',
    'edward':'rudy',
    'phil':'java'
}
friends=['phil','sarah']
for name in favorite_languages:
    if name in friends:
        print("Hi！"+name.title()+", I see your favorite language is "+favorite_languages[name].title()+"!")
    else:
        print("hi! "+name.title()+" Can we make a friend ?")
# 当name在friend列表中，打印与朋友的对话，反之则打印可以和我交朋友吗

hi! Jen Can we make a friend ?
Hi！Sarah, I see your favorite language id C!
hi! Edward Can we make a friend ?
Hi！Phil, I see your favorite language id Java!

顺序遍历

favorite_languages={
    'jen':'python',
    'sarah':'c',
    'edward':'rudy',
    'phil':'java'
}
for name in sorted(favorite_languages.keys()):
    print(name.title()+", thank you for taking the poll.")

Edward, thank you for taking the poll.
Jen, thank you for taking the poll.
Phil, thank you for taking the poll.
Sarah, thank you for taking the poll.

favorite_languages={
    'jen':'python',
    'sarah':'c',
    'edward':'rudy',
    'phil':'java',
    'lisa':'java'
}
for language in favorite_languages.values():
    print(language)
# keys()表示字典中所有的值
print("-----------")
​
for language in set(favorite_languages.values()):
    print(language)
# set()找不同,只打印不同的

python
c
rudy
java
java
-----------
java
c
rudy
python

嵌套

alien_1={'color':'green','point':5}
alien_2={'color':'green','point':5}
alien_3={'color':'green','point':5}
aliens=[alien_1,alien_2,alien_3]
for alien in aliens:
    print(alien)

{'color': 'green', 'point': 5}
{'color': 'green', 'point': 5}
{'color': 'green', 'point': 5}

aliens=[]
# 创建外星人空列表
​
for alien_number in range(30):
    new_alien = {'color':'green','point':5,'speed':'slow'}
    aliens.append(new_alien)
# 创建30个外星人
for alien in aliens[0:3]:
    if alien['color']=='green':
        alien['color']='yellow'
        alien['speed']='medium'
        alien['point']=10
# 修改前3个外星人
for alien in aliens[:5]:
    print(alien)
# 显示前五个外星人
print("...")
print("Total number of aliens: "+str(len(aliens)))
# 显示创建了几个外星人

{'color': 'yellow', 'point': 10, 'speed': 'medium'}
{'color': 'yellow', 'point': 10, 'speed': 'medium'}
{'color': 'yellow', 'point': 10, 'speed': 'medium'}
{'color': 'green', 'point': 5, 'speed': 'slow'}
{'color': 'green', 'point': 5, 'speed': 'slow'}
...
Total number of aliens: 30