title: Python: how to add a column to a pandas dataframe between two columns?
body: <p>I would like to add a column to a dataframe between two columns in number labeled columns dataframe. In the following dataframe the first column corresponds to the index while the first row to the name of the columns.</p>
  
  <pre><code>df
     0 0 1 2 3 4 5
     1 6 7 4 5 2 1
     2 0 3 1 3 3 4
     3 9 8 4 3 6 2 
  </code></pre>
  
  <p>I have <code>tmp=[2,3,5]</code> that I want to put between the columns <code>4</code> and <code>5</code>, so</p>
  
  <pre><code>df
     0 0 1 2 3 4 5 6 
     1 6 7 4 5 2 2 1
     2 0 3 1 3 3 3 4
     3 9 8 4 3 6 5 2 
  </code></pre>