title: Spark Change Column type failed
body: <pre><code>root
   |-- dt: timestamp (nullable = true)
   |-- AverageTemperature: double (nullable = true)
   |-- AverageTemperatureUncertainty: double (nullable = true)
   |-- City: string (nullable = true)
   |-- Country: string (nullable = true)
   |-- Latitude: string (nullable = true)
   |-- Longitude: string (nullable = true)
  </code></pre>
  <p>I have the above Data Schema from Spark. I am trying to change the type timestamp in dt to string</p>
  <pre><code>temperature_df.withColumn(&quot;dt&quot;,col(&quot;dt&quot;).cast(StringType()))
  </code></pre>
  <p>This is what I did, and I got the following error :</p>
  <pre><code>TypeError: 'list' object is not callable
  </code></pre>
  <p>Can someone explain to me why I got this error?</p>