title: combining python lists in savetxt
body: <p>I have 2 python lists that I want to save side by side using np.savetxt().</p>
  
  <p>I have tried:</p>
  
  <pre><code>np.savetxt('./filename.txt',np.hstack([list1,list2]),fmt=['%f','%f'])
  </code></pre>
  
  <p>but I get the error message</p>
  
  <pre><code>raise AttributeError('fmt has wrong shape.  %s' % str(fmt))
  AttributeError: fmt has wrong shape.  ['%f', '%f']
  </code></pre>
  
  <p>I don't know if it is relevant, but the lists are in decimal.Decimal format.</p>
  
  <p>What am I doing wrong please?</p>
  
  <hr>
  
  <p>edit: I originally said "vstack" but I meant "hstack".</p>