title: AttributeError: 'list' object has no attribute 'lower' in term frequency inverse document frequency
body: <p>I found lots of post in stack overflow related to this problem. I tried those but still getting the same error.
  I'm using python 3.7 &amp; wrote following code for my urdu data set</p>
  
  <pre><code>Tfidf_vect = TfidfVectorizer()
  
  x=Tfidf_vect.fit(df['final'])
  </code></pre>
  
  <p>But got error message <code>AttributeError: 'list' object has no attribute 'lower'</code> Then I found this stack overflow post<pre><a href="https://stackoverflow.com/questions/51497681/attributeerror-list-object-has-no-attribute-lower-clustering">AttributeError: &#39;list&#39; object has no attribute &#39;lower&#39; : clustering</a></pre>. It's suggesting TfidfVectorizer only requires a list of sentences
  So I follow the steps mentioned in solution &amp; modify the code &amp; use following code</p>
  
  <pre><code>vectors = TfidfVectorizer()
  dataset_list=df['final'].values.ravel().tolist()
  X = vectors.fit_transform(dataset_list)
  </code></pre>
  
  <p>Sample data set is available <a href="https://stackoverflow.com/questions/51497681/attributeerror-list-object-has-no-attribute-lower-clustering">here</a>
  Still the same error message.Can you suggest me the steps to correc?</p>