title: Problems appending columns from one excel file to another
body: <p>I seem to be unable to figure out how to append values from one excel file to another one.
  I have tried append mode numerous times but it fails each time due to encoding errors.
  I have sought solutions but none has turned out to solve my problem.</p>
  <p>I have two excel files which have a certain amount of rows. They have the same columns. I would like to append the rows from one file to the other.</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>import pandas as pd
  df = pd.read_excel("WindSpeed.xlsx",sheet_name=0 ,index_col=None)
  df.drop(df.columns[df.columns.str.contains('unnamed',case = False)],axis = 1, inplace = True)
  df['WindDirection']
  df=df[df['WindDirection'].astype(str).str.replace(',', '.').astype(int) &gt;= 315]
  df.to_excel('WindDirectionNorth.xlsx')
  
  df = pd.read_excel("WindSpeed.xlsx",sheet_name=0 ,index_col=None)
  df.drop(df.columns[df.columns.str.contains('unnamed',case = False)],axis = 1, inplace = True)
  df['WindDirection']
  df=df[df['WindDirection'].astype(str).str.replace(',', '.').astype(int) &lt;= 45]
  df.to_excel('WindDirectionNorth2.xlsx')
  
  
  f1 = open('WindDirectionNorth.xlsx', 'a+', encoding='utf8')
  f2 = open('WindDirectionNorth2.xlsx', 'r', encoding='utf8')
  
  f1.write(f2.read())
  f1.seek(0)
  f2.seek(0)
  
  f1.close()
  f2.close()</code></pre>
  </div>
  </div>
  </p>
  <p>This code brings me back the following error: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xf8 in position 14: invalid start byte</p>
  <p>If I out (rb) instead of (r) it returns the following error: ValueError: binary mode doesn't take an encoding argument</p>