title: Apply on Dataframe and getting: SettingWithCopyWarning: A value is trying to be set on a copy of a slice
body: <p>I always have used dataframe.apply(lambda x : f(x)) like follow and suddenly, only for this specific case, I am receiving this really annoying error message. As it is encapsulated in an App and Log are seen by users. It is pretty annoying</p>
  
  <pre><code>df_Holdings['Price'] = df_Holdings['Price'].apply(lambda x : round(x,6))
  </code></pre>
  
  <p>The error :</p>
  
  <blockquote>
    <p>2611: SettingWithCopyWarning: A value is trying to be set on a copy of
    a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] =
    value instead</p>
    
    <p>See the caveats in the documentation:
    <a href="http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy" rel="nofollow noreferrer">http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy</a></p>
  </blockquote>
  
  <p>I tried also this way but received a deeper error message:</p>
  
  <pre><code>df_Holdings.loc[:, 'Price'] = df_Holdings.loc[:, 'Price'].apply(lambda x : round(x,6))
  </code></pre>
  
  <p>The error:</p>
  
  <blockquote>
    <p>C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\indexing.py:543:
    SettingWithCopyWarning: A value is trying to be set on a copy of a
    slice from a DataFrame. Try using .loc[row_indexer,col_indexer] =
    value instead</p>
    
    <p>See the caveats in the documentation:
    <a href="http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy" rel="nofollow noreferrer">http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy</a>
    self.obj[item] = s</p>
  </blockquote>
  
  <p>Is this really this row really having an issue?
  Thanks for your help.</p>