title: Pandas Mixed Type to Integer
body: <p>Given the following data frame:</p>
  
  <pre><code>import pandas as pd
  df = pd.DataFrame(
          {'A':['A','B','C','D'],
           'C':['1','12','*','8']
          })
  df
  
      A   C
  0   A   1
  1   B   12
  2   C   *
  3   D   8
  </code></pre>
  
  <p>I'd like to remove all instances of '*' and convert the rest to integer.
  There may be some instances of 'nan' or 'NaN' in my actual data.</p>