擅长:python、mysql、java
<p>将列表理解转换为常规循环的最常用方法如下:</p>
<pre class="lang-py prettyprint-override"><code>l = [f(x) for x in iter]
# converts to:
l = []
for x in iter:
l.append(f(x))
</code></pre>
<p>当您在理解中创建嵌套列表时,这会变得有点复杂,但遵循相同的逻辑,现在<code>f(x)</code>是列表comp本身的翻译。因此,我们:</p>
<pre class="lang-py prettyprint-override"><code>l = [[g(x) for x in sub] for sub in iter]
# converts to:
l = []
for sub in iter:
temp = []
for x in sub:
temp.append(g(x))
l.append(temp)
</code></pre>
<p>因此,在您的情况下,只需添加条件,列表comp就变成:</p>
<pre class="lang-py prettyprint-override"><code>sep_class = [[x for x, t in zip(X_train, y_train)if t ==c] for c in np.unique(y_train)]
# converts to:
sep_class = []
for c in np.unique(y_train):
sub = []
for x, t in zip(X_train, y_train):
if t == c:
sub.append(x)
sep_class.append(sub)
</code></pre>