title: Drop function in Pandas is changing original dataframe?
body: <p>I am using drop in pandas with an inplace=True set. I am performing this on a duplicate dataframe, but the original dataframe is also being modified.</p>
  
  <pre><code>df1 = df
  for col in df1.columns:
     if df1[col].sum() &gt; 1:
        df1.drop(col,inplace=True,axis=1)
  </code></pre>
  
  <p>This is modifying my 'df' dataframe and don't seem to understand why.</p>