title: How can I implement a fill na with avg using rolling window of 7 days in pyspark
body: <p>I have a pyspark df as follow:</p>
  <p><img src="https://i.stack.imgur.com/fEDo2.png" alt="1" /></p>
  <p>How can I use fill na to fill with average values in a 7 days rolling window, but corresponding to the category value, for instance, desktop to desktop, mobile to mobile, etc..</p>