擅长:python、mysql、java
<p>dictionary的setdefault是更新现有dict条目(如果存在)或创建新条目(如果不是一次完成的话)的好方法:</p>
<p>循环样式:</p>
<pre><code># This is our sample data
data = [("Milter", "Miller", 4), ("Milter", "Miler", 4), ("Milter", "Malter", 2)]
# dictionary we want for the result
dictionary = {}
# loop that makes it work
for realName, falseName, position in data:
dictionary.setdefault(realName, {})[falseName] = position
</code></pre>
<p>字典现在等于:</p>
<pre><code>{'Milter': {'Malter': 2, 'Miler': 4, 'Miller': 4}}
</code></pre>