title: Add column to pyspark dataframe based on a condition
body: <p>My data.csv file has three columns like given below. I have converted this file to python spark dataframe. <br></p>
  
  <pre><code>  A   B    C
  | 1 | -3 | 4 |
  | 2 | 0  | 5 |
  | 6 | 6  | 6 |
  </code></pre>
  
  <p>I want to add another column D in spark dataframe with values as Yes or No based on the condition that if corresponding value in B column is greater than 0 then yes otherwise No.</p>
  
  <pre><code>  A   B    C   D
  | 1 | -3 | 4 | No  |
  | 2 | 0  | 5 | No  |
  | 6 | 6  | 6 | Yes |
  </code></pre>
  
  <p>I am not able to implement this through PySpark dataframe operations.</p>