title: how to fix ''nothing to repeat at position 2''
body: <p>ı am trying to stemmize words in tex of dataframe</p>
  
  <p>data is a dataframe , karma is text column , zargan is the dict of word and root of word </p>
  
  <pre><code>for a in range(1,100000):
      for j in data.KARMA[a].split():
          pattern = r'\b'+j+r'\b' 
          data.KARMA[a] = re.sub(pattern, str(zargan.get(j,j)),data.KARMA[a]) 
  print(data.KARMA[1])
  </code></pre>
  
  <p>I want to change the word and root in the texts</p>