title: How to select all but the 3 last columns of a dataframe in Python
body: <p>I want to select all but the 3 last columns of my dataframe.</p>
  
  <p>I tried :</p>
  
  <pre><code>df.loc[:,-3]
  </code></pre>
  
  <p>But it does not work</p>
  
  <p>Edit : title</p>