title: The 20 newsgroups dataset comprises around 18000 newsgroups posts, while sklearn loads only about half of the dataset, why is that?
body: <p>The <a href="https://scikit-learn.org/0.19/datasets/twenty_newsgroups.html" rel="nofollow noreferrer">20 newsgroups dataset</a> comprises around 18000 newsgroups posts on 20 topics split in two subsets.</p>
  
  <p>while sklearn loads only about half of the dataset</p>
  
  <pre><code>&gt;&gt;&gt; from sklearn.datasets import fetch_20newsgroups
  &gt;&gt;&gt; newsgroups_train = fetch_20newsgroups(subset='train')
  &gt;&gt;&gt; newsgroups_train.filenames.shape
  (11314,)
  </code></pre>
  
  <p>why does sklearn only loads about half of the dataset?</p>