python学习笔记（二）—— 字典

 

字典的练习

#字典存储外星人的颜色和点数
alien_0 = {"color":"green","points":5}
print(alien_0["color"])
print(alien_0["points"])

遍历字典

#key-value
favorite_languages = {
    "jen" : "python",
    "sarah" : "c",
    "edwrd" : "ruby",
    "phil" : "python",
}
for name, language in favorite_languages.items():
    print(name.title()+"'s favorite language is " + language.title() + ".")

遍历字典中所有key,用keys()方法

for name in favorite_languages.keys():
    print(name.title())

if "erin" not in favorite_languages.keys():
    print("Erin, please take our poll")

按顺序遍历字典中所有键（利用sorted()函数）

for name in sorted(favorite_languages.keys()):
    print(name.title())

遍历字典中所有的值，使用values()方法

for language in favorite_languages.values():
    print(language.title())

剔除重复项，可使用集合set

for language in set(favorite_languages.values()):
    print(language.title())

有时候需要将一系列字典存储在列表中，或将列表作为值存储在字典中

#字典列表，在列表中存储字典
alien_0 = {'color':'green','points':2}
alien_1 = {'color':'yellow','points':4}
alien_2 = {'color':'red','points':6}
aliens = [alien_0,alien_1,alien_2]
for alien in aliens:
    print(alien)

 

#字典列表练习2
#创建一个空列表
aliens = []
#创建30个alien
for alien_number in range(0,30):
    new_alien = {'color':'green','points':2,'speed':'slow'}
    aliens.append(new_alien)
for alien in aliens[0:3]:
    if alien['color'] == 'green':
        alien['color'] = 'yellow'
        alien['points'] = 4
        alien['speed'] = 'medium'
for alien in aliens[0:5]:
    print(alien)
print('...')

在字典中存储列表

pizza = {'crust':'thick','toppings':['mushrooms','extra cheese']}
print("Your ordered a " + pizza['crust'] + "- crust pizza " + "with the following toppings:")
for topping in pizza['toppings']:
    print("\t" + topping)

在字典中存储字典

users = {'aeinstein':{'first':'albert','last':'einstein','location':'princetion'},'mcurie':{'first':'marie','last':'curie','location':'paris'}}
for username,user_info in users.items():
    print("\nUsername: " + username)
    full_name = user_info['first'] + " " + user_info['last']
    location = user_info['location']
    print("\tFull name : " + full_name.title())
    print("\tLocation : " + location.title())