擅长:python、mysql、java
<p>使用<code>setdefault</code></p>
<p><strong>Ex:</strong></p>
<pre><code>data = [["Bob","Algebra",5],["Bob","History",4],["Bob","Physics",7],["Bob","Astronomy",5],["Allen","Algebra",5],["Allen","History",4],["Allen","Physics",7],["Mary","Algebra",5],["Mary","History",3],["Mary","Physics",7],["Mary","Astronomy",8]]
result = {}
for k, sub, _ in data:
result.setdefault(k, []).append(sub) #Set first element as key and append subject as value
print([[k] + v for k, v in result.items()]) #Form required list
</code></pre>
<p><strong>输出:</strong></p>
<pre><code>[['Bob', 'Algebra', 'History', 'Physics', 'Astronomy'],
['Allen', 'Algebra', 'History', 'Physics'],
['Mary', 'Algebra', 'History', 'Physics', 'Astronomy']]
</code></pre>