python - Python 3.4 中的 KeyError

Question

我用python制作了一本字典，到目前为止，当我这样打印它时没有任何问题：

print(video_game_company)

我会得到预期的结果：

{('Street Fighter IV', 'Resident Evil 4'): 'Capcom', ('Crash Bandicoot', 'Uncharted', 'The Last of Us'): 'Naughty Dog', ('Prince of Persia: The Forgotten Sands', "Assassin's Creed", 'Watch Dogs'): 'Ubisoft'}

指标如下：

1. 育碧
2. 卡普空
3. 顽皮狗

但是当我输入：

print("%s" % video_game_company["Capcom"])

我收到以下错误：

KeyError: 'Capcom'

我究竟做错了什么？

Answer 1

"Capcom" is not a key in the dictionary.It's a value for the key ('Street Fighter IV', 'Resident Evil 4').So video_game_company['Capcom'] results in a keyError(Obviously....since there is no such key 'Capcom').

Answer 2

__getitem__在字典上获取键'Capcom'等是值 - 因此是错误。

您应该切换每个键和值以获得所需的行为：

{'Ubisoft': ('Prince of Persia: The Forgotten Sands', "Assassin's Creed", 'Watch Dogs'), 'Naughty Dog': ('Crash Bandicoot', 'Uncharted', 'The Last of Us'), 'Capcom': ('Street Fighter IV', 'Resident Evil 4')}

---

现在它可以正常工作了：

print("%s" % video_game_company["Capcom"])
# ('Street Fighter IV', 'Resident Evil 4')

Answer 3

“Capcom”、“Ubisoft”和“Naughty Dog”是字典的值而不是键。

print("%s" % video_game_company[('Street Fighter IV', 'Resident Evil 4')])  
# display Capcom

您需要反转 dict 中的键和值才能执行此操作video_game_company["Capcom"]

video_game_company = {'Ubisoft': ('Prince of Persia: The Forgotten Sands', "Assassin's Creed", 'Watch Dogs'),
                      'Naughty Dog': ('Crash Bandicoot', 'Uncharted', 'The Last of Us'), 
                      'Capcom': ('Street Fighter IV', 'Resident Evil 4')}

print("%s" % video_game_company["Capcom"])
# displays ('Street Fighter IV', 'Resident Evil 4')