title: Match columns and append to data frame, Python 3.6
body: <p>I have around 50 excel files &amp; I want to import to dataframe and merge all files into single dataframe.
  But some file has 3 some are 4 columns. Every file as different columns in different order.</p>
  
  <p>Total distinct column from all the files: 5 i.e col1, col2, col3, col4, col5</p>
  
  <p>I know how to import but while appending facing issue.</p>
  
  <p>Script:</p>
  
  <pre><code>dfAll = pd.DataFrame(columns=['col1', 'col2', 'col3', 'col4', 'col5')]
  df= pd.read_excel('FilePath', sheetname='data1') # contains 3 columns i.e col1, col2, col5
  columnsOFdf = df.columns
  dfAll[columnsOFdf] = dfAll.append(df)
  </code></pre>
  
  <p>but its giving error "ValueError: Columns must be same length as key"</p>
  
  <p>I want to append <strong>df['col1','col2','col5']</strong> data to <strong>dfAll['col1','col2','col5']</strong></p>
  
  <p>Please help on this issue.</p>