title: Restructure word list into two columns
body: <p>If I have columns of lists, is there a pandas function that lets me split each word which is separated by a comma to return two new columns, one column represents the first word which can not connect by itself and the second column represents the connected word. In general the idea is to create a word table of the different words and compare them together in two columns. The following table is used for a better interpretation of the problem.</p>
  
  <pre><code>import pandas as pd
  
  r1=['tag1','tag2', 'tag3', 'tag4']
  
  df=pd.DataFrame(r1,columns=['text'])
  </code></pre>
  
  <p>Desired Outcome, first column shows the first word, the second column represents the connected word. This process is also vice versa, for the next words in the lists.:  </p>
  
  <pre><code>col1  |  col2
  --------------
  tag1  |  tag2
  tag1  |  tag3    
  tag1  |  tag4
  tag2  |  tag1
  tag2  |  tag3
  tag2  |  tag4
  tag3  |  tag1
  tag3  |  tag2
  tag3  |  tag4
  tag4  |  tag1
  tag4  |  tag2
  tag4  |  tag3
  </code></pre>