title: In a string dataframe, How to check casting capability into a float?
body: <p>I have a manual dataset where a column <code>TPI_kW</code> is supposed to have float values.
  It is stored into a dataframe 'df_data'.</p>
  <p>I try to cast <code>TPI_kW</code> with :</p>
  <pre><code>df_data[`TPI_kW`] = df_data[`TPI_kW`].astype(float)
  </code></pre>
  <p>i got this error :</p>
  <pre><code>ValueError: could not convert string to float: '*94'
  </code></pre>
  <p>this value is indeed in my column :</p>
  <pre><code>df_data[df_data['TPI_kW'] == '*94']['TPI_kW']
  
  Out[5]: 
  Timestamp
  2021-01-14 18:00:00    *94
  Name: TPI_kW, dtype: object
  </code></pre>
  <p>If this kind of error is recurrent, it's very boring to search for all of them..</p>
  <p>I'm wondering if there is a way to check (efficiently) casting capability into a float, before raising an error. And maybe replace the error value with <code>np.nan</code> ?</p>
  <p>Best regards !</p>