title: Getting specific field from chosen Row in Pyspark DataFrame
body: <p>I have a Spark DataFrame built through <em>pyspark</em> from a JSON file as </p>
  
  <pre><code>sc = SparkContext()
  sqlc = SQLContext(sc)
  
  users_df = sqlc.read.json('users.json')
  </code></pre>
  
  <p>Now, I want to access a <em>chosen_user</em> data, where this is its _id field. I can do</p>
  
  <pre><code>print users_df[users_df._id == chosen_user].show()
  </code></pre>
  
  <p>and this gives me the full Row of the user. But suppose I just want one specific field in the Row, say the user gender, how would I obtain it?</p>