title: How to get a non-shuffled train_test_split in sklearn
body: <p>If I want a random train/test split, I use the sklearn helper function:</p>
  
  <pre><code>In [1]: from sklearn.model_selection import train_test_split
     ...: train_test_split([1,2,3,4,5,6])
     ...:
  Out[1]: [[1, 6, 4, 2], [5, 3]]
  </code></pre>
  
  <p>What is the most concise way to get a non-shuffled train/test split, i.e.</p>
  
  <pre><code>[[1,2,3,4], [5,6]]
  </code></pre>
  
  <p><strong>EDIT</strong> Currently I am using</p>
  
  <pre><code>train, test = data[:int(len(data) * 0.75)], data[int(len(data) * 0.75):] 
  </code></pre>
  
  <p>but hoping for something a little nicer. I have opened an issue on sklearn
  <a href="https://github.com/scikit-learn/scikit-learn/issues/8844" rel="noreferrer">https://github.com/scikit-learn/scikit-learn/issues/8844</a></p>
  
  <p><strong>EDIT 2:</strong> My PR has been merged, in scikit-learn version 0.19, you can pass the parameter <code>shuffle=False</code> to <code>train_test_split</code> to obtain a non-shuffled split.</p>