title: Replace values that are not INT with 0 in Pandas DataFrame
body: <p>I have a column in a <code>pandas DataFrame</code> which looks like this.</p>
  
  <pre><code> ----------
  |audi_id   |
   ----------
  |     1    |
  |     2    |
  |     3    |
  |     4    |
  |    abc   |
  -----------
  </code></pre>
  
  <p>I need to replace any value that contains a string value, with a 0.</p>
  
  <p>I currently have this code here to replace all non <code>int</code> values to <code>str</code> but it doesn't seem to be working. Can anyone please help?</p>
  
  <pre><code>ValueError: Can only tuple-index with a MultiIndex
  </code></pre>
  
  <p>-</p>
  
  <pre><code>df['test'] = pd.to_numeric(df.audit_id[:, 0], errors='coerce').fillna(0)
  </code></pre>
  
  <p>Output I expect is:</p>
  
  <pre><code> ----------
  |audi_id   |
   ----------
  |     1    |
  |     2    |
  |     3    |
  |     4    |
  |     0    |
  -----------
  </code></pre>