1 python是使用{}来表示字典
字典是一系列的键值对
alien_0={'color':'green','point':5}
2 访问字典中的值
new_point = alien_0['point'] print("you just earned "+str(new_point)+" points!")
3 添加,修改,空,删除 字典
alien_0 = {} alien_0['color'] = 'green' alien_0['point'] =5 print(alien_0) alien_0 = {'color':'green'} print("The alien is "+alien_0['color']+".") alien_0['color'] = 'yellow' print("The alien is " + alien_0['color'] + ".")
alien_0 = {'x_position':0,'y_position':25,'speed':'medium'} print("Original x-position:" + str(alien_0['x_position'])) if alien_0['speed'] == 'slow': x_increment = 1 elif alien_0['speed'] == 'medium': x_increment = 2 else : x_increment = 3 alien_0['x_position'] = alien_0['x_position'] + x_increment print('New x-position:' + str(alien_0['x_position'])) alien_0 = {'color':'green','point':5} print(alien_0) del alien_0['point'] print(alien_0)
多行输入
favorite_lanage = { 'jen':'python', 'sarah':'c', 'edward':'ruby', 'phil':'python', } print("sarah's favorite language is " + favorite_lanage['sarah'].title()+ ".")
4 遍历字典
user_0 = { 'username':'efermi', 'first':'enrico', 'last':'erimi', } for key,value in user_0.items(): print(' key:' + key) print('Value:' + value)
key和value可以自定义
5遍历字典中的所有键
favorite_lanage = { 'jen':'python', 'sarah':'c', 'edward':'ruby', 'phil':'python', } for name in favorite_lanage.keys(): print(name.title())
6按照顺序遍历字典中的所有键
favorite_lanage = { 'jen':'python', 'sarah':'c', 'edward':'ruby', 'phil':'python', } for name in sorted(favorite_lanage.keys()): print(name.title() + ", thank you for taking the poll.")
7 遍历字典中的值
favorite_lanage = { 'jen':'python', 'sarah':'c', 'edward':'ruby', 'phil':'python', } for name in favorite_lanage.values(): print(name.title() + ", have been mentioned.")
8 去重用 set()
favorite_lanage = { 'jen':'python', 'sarah':'c', 'edward':'ruby', 'phil':'python', } for name in set(favorite_lanage.values()): print(name.title() + ", have been mentioned.")
9 嵌套
把字典存储在列表中,或者把列表作为值存储在字典中,这叫做嵌套
alien_0 = {'color':'green','points':5} alien_1 = {'color':'yellow','points':10} alien_2 = {'color':'red', 'points':15} aliens = [alien_0,alien_1,alien_2] for alien in aliens: print(alien)
aliens = [] for alien_number in range(30): new_alien = {'color':'green','points':5,'speed':'slow'} aliens.append(new_alien) for alien in aliens[:3]: if alien['color']=='green': alien['color']='yellow' alien['speed']='medium' alien['points']=10 for alien in aliens[0:5]: print(alien) print('...')
10 字典中存储列表
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: print(" " + language.title())
11 字典中存储字典
users = { 'aeinstein': { 'first':'albert', 'last':'einstein', 'location':'princeton', }, 'mcurie':{ 'first':'marie', 'last':'curie', 'location':'paris', } } for username,user_info in users.items(): print(" username: " +username) full_name = user_info['first']+" "+user_info['last'] location = user_info['location'] print(" full name:"+full_name.title()) print(" location:"+location.title())