字典

建立空字典

alien_0 = {}
print(alien_0)
输出:
{}

删除键值对

alien_0 = {'color': 'green','points':'5'}
del alien_0['color']
print(alien_0)
输出：
{'points': '5'}

遍历键值对

user_0 = {
    'username':'efermi',
    'first':'enrico',
    'last':'fermi'
    }
for key,value in user_0.items():
    print("
Key: " + key)
    print("Value: " + value)

输出：
Key: username
Value: efermi

Key: first
Value: enrico

Key: last
Value: fermi

遍历字典中的所有键

favorite_languages = {
    'jen':'python',
    'sarah':'c',
    'edward':'ruby',
    'phil':'python'
    }
for name in favorite_languages.keys():
#上行等同于：for name in favorite_languages:  #(遍历字典时，会默认遍历所有的键)

print(name.title())
输出：
Jen
Sarah
Edward
Phil

遍历字典中的所有值

favorite_languages = {
    'jen':'python',
    'sarah':'c',
    'edward':'ruby',
    'phil':'python'
    }
for value in set(sorted(favorite_languages.values())):  #values()：取值；sorted()：排序；set()：剔重
    print(value.title())
输出：
Ruby
C
Python

嵌套：

字典中嵌套列表：打印每人最爱的语言

favorite_languages= {
    'jen':['python','ruby'],
    'sarah':['c'],
    'edward':['ruby','go'],
    'phil':['python','haskell']
    }
    
for name,languages in favorite_languages.items():
    print('
' + name.title() + "'s favorite languages are:" )
    for language in languages:    #注意：language与lanuages不同
        print("	" + language.title())
输出：

Jen's favorite languages are:
        Python
        Ruby

Sarah's favorite languages are:
        C

Edward's favorite languages are:
        Ruby
        Go

Phil's favorite languages are:
        Python
        Haskell

字典中嵌套字典：

users = {
    'aeinstein':{
        'first':'albert',
        'last':'einstein',
        'location':'princeton'
        },
    'mcurie':{
        'first':'marie',
        'last':'curie',
        'location':'paris'
        }
    }

for keys,values in users.items():
    print("
" + keys + ":")
    full_name = values['first'] +' ' + values['last']
    location = values['location']
    print("	 full_name: " + full_name)
    print("	  location: " + location)

输出：

aeinstein:
         full_name: albert einstein
          location: princeton

mcurie:
         full_name: marie curie
          location: paris