title: pandas df seems not showing histogram, though data seems to be numeric
body: <p>I have the following data:</p>
  
  <pre><code>23345355,USA, ,1/8/2016,5411,  ,18.31, ,95448
  268035111,USA, ,1/8/2016,5921,  ,15.22, ,90266
  35940332,USA, ,1/26/2016,5651,  ,121.94, ,91306
  4211391,   , ,12/31/2015,0,  ,44.40, ,     
  319878537,USA, ,12/29/2015,5814,04,0.86, ,90029
  117039647,ESP, ,1/2/2016,3535,  ,372.38, ,08019
  246311053,USA, ,1/11/2016,7523,  ,1.50, ,11101
  953217,USA, ,1/29/2016,5968,  ,29.70, ,95032
  270542768,USA, ,1/17/2016,7832,  ,18.30, ,40503
  42855400,   , ,1/6/2016,0,  ,50.00, ,     
  190065824,   , ,12/31/2015,0,  ,120.00, ,     
  243492296,USA, ,1/25/2016,5331,  ,6.89, ,40810
  102483965,US , ,12/31/2015,5814,  ,25.00, ,19341
  </code></pre>
  
  <p>I want to look at the last column, and do a histogram, so, I did (df is the pandas df)</p>
  
  <pre><code>df = df[df[LAST_COLUMN].apply(lambda x: x.isnumeric())]
  </code></pre>
  
  <p>This way I cleaned up the elements that are not numeric (which I checked and worked).</p>
  
  <p>However, when I do a df.hist(), I get histograms only for columns 0,4 and 6, not for column 8 (LAST_COLUMN). It looks like some element is not numeric, but I checked and they all are numeric.</p>
  
  <p>Why is that?</p>