title: how to use word_tokenize in data frame
body: <p>I have recently started using the nltk module for text analysis. I am stuck at a point. I want to use word_tokenize on a dataframe, so as to obtain all the words used in a particular row of the dataframe.</p>
  
  <pre><code>data example:
         text
  1.   This is a very good site. I will recommend it to others.
  2.   Can you please give me a call at 9983938428. have issues with the listings.
  3.   good work! keep it up
  4.   not a very helpful site in finding home decor. 
  
  expected output:
  
  1.   'This','is','a','very','good','site','.','I','will','recommend','it','to','others','.'
  2.   'Can','you','please','give','me','a','call','at','9983938428','.','have','issues','with','the','listings'
  3.   'good','work','!','keep','it','up'
  4.   'not','a','very','helpful','site','in','finding','home','decor'
  </code></pre>
  
  <p>Basically, i want to separate all the words and find the length of each text in the dataframe.</p>
  
  <p>I know word_tokenize can for it for a string, but how to apply it onto the entire dataframe?</p>
  
  <p>Please help!</p>
  
  <p>Thanks in advance...</p>