擅长:python、mysql、java
<pre><code> l2 = [j for i in l1 for j in 3*[i]]
</code></pre>
<p>这使得:</p>
<pre><code> ['one', 'one', 'one', 'two', 'two', 'two', 'three', 'three', 'three']
</code></pre>
<p>这相当于:</p>
<pre><code>l2 = []
for i in l1:
for j in 3*[i]:
l2.append(j)
</code></pre>
<p>注意<code>3*[i]</code>创建了一个包含3个重复元素的列表(例如<code>['one', one', 'one']</code>)</p>