A value is trying to be set on a copy of a slice from a DataFrame Warning
<p>Not sure why I still get the warning after I updated to .loc method suggested by the message? Is it a false alarm?</p>

<pre><code>eG.loc[:,'wt']=eG.groupby(['date','BB'])['m'].transform(weightFunction)
</code></pre>

<blockquote>
  <p>A value is trying to be set on a copy of a slice from a DataFrame</p>
</blockquote>

<pre><code>See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  if __name__ == '__main__':
</code></pre>