title: Add PySpark RDD as new column to pyspark.sql.dataframe
body: <p>I have a pyspark.sql.dataframe where each row is a news article. I then have a RDD that represents the words contained in each article. I want to add the RDD of words as a column named 'words' to my dataframe of new articles. I tried </p>
  
  <pre><code>df.withColumn('words', words_rdd )
  </code></pre>
  
  <p>but I get the error</p>
  
  <pre><code>AssertionError: col should be Column
  </code></pre>
  
  <p>The DataFrame looks something like this</p>
  
  <pre><code>Articles
  the cat and dog ran
  we went to the park
  today it will rain
  </code></pre>
  
  <p>but I have 3k news articles.</p>
  
  <p>I applied a function to clean the text such as remove stop words and I have a RDD that looks like this:</p>
  
  <pre><code>[[cat, dog, ran],[we, went, park],[today, will, rain]]
  </code></pre>
  
  <p>I'm trying to get my Dataframe to look like this:</p>
  
  <pre><code>Articles                 Words
  the cat and dog ran      [cat, dog, ran]
  we went to the park      [we, went, park]
  today it will rain       [today, will, rain]
  </code></pre>