title: Converting empty strings to 0 using Numpy
body: <p>I have a numpy array where each element looks something like this:</p>
  
  <pre><code>['3' '1' '35' '0' '0' '8.05' '2']
  ['3' '1' '' '0' '0' '8.4583' '0']
  ['1' '1' '54' '0' '0' '51.8625' '2']
  </code></pre>
  
  <p>I would like to replace all empty strings like the ones in the second row above, with some default value like 0. How can I do this with numpy?</p>
  
  <p>The ultimate goal is to be able to run this: <code>S.astype(np.float)</code>, but I suspect the empty strings are causing problems in the conversion.</p>