title: Copy pandas dataframe to excel using openpyxl
body: <p>I have some complicated formating saved in a template file into which I need to save data from a pandas dataframe. Problem is when I use pd.to_excel to save to this worksheet, pandas overwrites the formatting. Is there a way to somehow 'paste values' form the df into the worksheet? I am using pandas 0.17</p>
  
  <pre><code>import openpyxl
  import pandas as pd
  wb= openpyxl.load_workbook('H:/template.xlsx')
  sheet = wb.get_sheet_by_name('spam')
  sheet.title = 'df data'
  wb.save('H:/df_out.xlsx')
  
  xlr = pd.ExcelWriter('df_out.xlsx')
  df.to_excel(xlr, 'df data')
  xlr.save()
  </code></pre>