title: What is [:,:-1] in python?
body: <p>I just started learning ML myself in python.
  I didn't understand a passage in the code and would be happy if you made it clear to me what he was saying.
  Plus I don't know what <code>[:, -1]</code> and <code>[:,: - 1]</code> do</p>
  
  <pre><code>inputs = training_data[:,:-1]
  outputs = training_data[:, -1]
  </code></pre>