如何在Python中从两个字典创建dict？

Question

我现在正在处理Python dicts。我写了一个代码：

import random

categories = {1 : "Antics", 2 : "Tickets", 3: "Moviez",
              4 : "Music", 5 : "Photography", 6 : "Gamez", 7 : "Bookz",
              8 : "Jewelry", 9 : "Computers", 10 : "Clothes"}

items = {"Picture" : 1, "Clock" : 1, "Ticket for Mettalica concert" : 2,
         "Ticket for Iron Maiden concert" : 2, "Ticket for Placebo concert" : 2,
         "The pianist" : 3, "Batman" : 3, "Spider-Man" : 3,
         "WoW" : 6, "Cabal" : 6, "Diablo 3" : 6, "Diablo 2" : 6,
         "Thinking in Java" : 7, "Thinking in C++" : 7, "Golden ring" : 8,
         "Asus" : 10, "HP" : 10, "Shoes" : 11}

for key, val in categories :
    for k, v in items :
        if key == v :
            print(val, k)

我想创建第三个dict，在那里我可以得到如下内容：

^{pr2}$

所以继续。在

怎么做？我的代码显示：

test.py, line 14, in <module>
    for key, val in categories :
TypeError: 'int' object is not iterable

Answer 1

将代码更改为：

for key, val in categories.iteritems():
    for k, v in items.iteritems():
        if key == v:
            print(val, k)

通过这种方式，您可以使用iteiteiterator在键/值对上进行迭代，对于大型字典，它的性能优于items()。在

你想要的是这样的：

^{pr2}$

它产生了

{'Tickets': set(['Ticket for Mettalica concert', 'Ticket for Placebo concert',
    'Ticket for Iron Maiden concert']),
'Jewelry': set(['Golden ring']),
'Antics': set(['Picture', 'Clock']),
'Moviez': set(['Batman', 'Spider-Man', 'The pianist']),
'Bookz': set(['Thinking in Java', 'Thinking in C++']),
'Gamez': set(['Diablo 3', 'Diablo 2', 'WoW', 'Cabal']),
'Clothes': set(['Asus', 'HP'])}