擅长:python、mysql、java
<p><a href="http://scikit-learn.org/stable/modules/generated/sklearn.decomposition.PCA.html" rel="nofollow noreferrer">documentation</a>说明了<code>0 < n_components < 1</code>的情况:</p>
<blockquote>
<p>if <code>0 < n_components < 1</code> and svd_solver == 'full', </p>
<p>select the number
of components such that the amount of variance that needs to be
explained is greater than the percentage specified by n_components.</p>
</blockquote>
<p>如果你提到这样的话,你会更清楚:</p>
<blockquote>
<p>if <code>0 < n_components < 1</code> and svd_solver == 'full', </p>
<p>select the minimum number of components from the sorted list (descending order)
according to their respective explained variance values such that the amount of
variance that needs to be explained is greater than the percentage specified by n_components</p>
</blockquote>
<p>这样就不会有歧义了。在</p>
<p>之后:</p>
<p><code>PCA(0.71)</code>将返回PC1和PC2</p>
<p><code>PCA(0.005)</code>-(不太可能的情况)将返回PC1</p>