擅长:python、mysql、java
<p>使用<code>defaultdict</code>:</p>
<pre><code>from collections import defaultdict
country_names = defaultdict(int)
for i in country_city_tuples:
country_names[i[0]]+=1
country_names
defaultdict(int, {'Netherlands': 4, 'Spain': 4, 'Italy': 2})
</code></pre>