title: Concat empty data frame with another Dataframe in pandas with python
body: <p>I have an empty dataframe of 14 rows with nan values created as below:</p>
  <pre><code>dfs_empty_rows = pd.DataFrame(data=[[np.nan] * len(interm_df.columns)] * 14, columns=[np.nan] * len(interm_df.columns))
  </code></pre>
  <p>I want to concat interm_df, which was values with dfs_empty_rows so that the forst 14 rows are blank in the new dataframe.
  I am trying to concat using:</p>
  <pre><code>pd.concat([dfs_empty_rows,df], axis=0, ignore_index=True)
  </code></pre>
  <p>But this is giving an error :</p>
  <pre><code>InvalidIndexError: Reindexing only valid with uniquely valued Index objects
  </code></pre>
  <p>How can i concat an empty df with another df with values.</p>
  <p>Output should be concat of empty df with values df in order.</p>