title: How to select all columns except one in pandas?
body: <p>I have a dataframe that look like this:</p>
  <pre><code>import pandas as pd
  import numpy as np
  df = pd.DataFrame(np.random.rand(4,4), columns=list('abcd'))
  df
        a         b         c         d
  0  0.418762  0.042369  0.869203  0.972314
  1  0.991058  0.510228  0.594784  0.534366
  2  0.407472  0.259811  0.396664  0.894202
  3  0.726168  0.139531  0.324932  0.906575
  </code></pre>
  <p>How I can get all columns except <code>b</code>?</p>