title: insert space between regex match
body: <p>I want to un-join typos in my string by locating them using regex and insert a space character between the matched expression. </p>
  
  <p>I tried the solution to a similar question ... but it did not work for me -(<a href="https://stackoverflow.com/questions/38998547/insert-space-between-characters-regex">Insert space between characters regex</a>); solution-  to use the replace string as '\1 \2' in re.sub .</p>
  
  <pre><code>import re
  
  corpus = ''' 
  This is my corpus1a.I am looking to convert it into a 2corpus 2b.
  '''
  
  clean = re.compile('\.[^(\d,\s)]')
  corpus = re.sub(clean,' ', corpus)
  
  clean2 = re.compile('\d+[^(\d,\s,\.)]')
  corpus = re.sub(clean2,'\1 \2', corpus)
  </code></pre>
  
  <p>EXPECTED OUTPUT:</p>
  
  <pre><code>This is my corpus 1 a. I am looking to convert it into a 2 corpus 2 b.
  </code></pre>