title: How to change the order of DataFrame columns?
body: <p>I have the following <code>DataFrame</code> (<code>df</code>):</p>
  
  <pre><code>import numpy as np
  import pandas as pd
  
  df = pd.DataFrame(np.random.rand(10, 5))
  </code></pre>
  
  <p>I add more column(s) by assignment:</p>
  
  <pre><code>df['mean'] = df.mean(1)
  </code></pre>
  
  <p>How can I move the column <code>mean</code> to the front, i.e. set it as first column leaving the order of the other columns untouched?</p>