<p>试一试</p>
<pre><code>from collections import defaultdict
countries_dict = {'Andorra': ('Europe', 'Andorra la Vella'),
'Afghanistan': ('Asia', 'Kabul'),
'Antigua and Barbuda': ('North America', "St. John's"),
'Albania': ('Europe', 'Tirana'),
'Armenia': ('Asia', 'Yerevan'),
'Angola': ('Africa', 'Luanda'),
'Argentina': ('South America', 'Buenos Aires'),
'Austria': ('Europe', 'Vienna'),
'Australia': ('Oceania', 'Canberra'),
'Azerbaijan': ('Asia', 'Baku'),
'Barbados': ('North America', 'Bridgetown'),
'Bangladesh': ('Asia', 'Dhaka'),
'Belgium': ('Europe', 'Brussels')}
d = defaultdict(list)
for k,v in countries_dict.items():
d[v[0]].append(k)
print(d)
</code></pre>
<p>输出</p>
<pre><code>defaultdict(<class 'list'>, {'Europe': ['Andorra', 'Albania', 'Austria', 'Belgium'], 'Asia': ['Afghanistan', 'Armenia', 'Azerbaijan', 'Bangladesh'], 'North America': ['Antigua and Barbuda', 'Barbados'], 'Africa': ['Angola'], 'South America': ['Argentina'], 'Oceania': ['Australia']})
</code></pre>