Spark convert single column into array
<p>How can I convert a single column in spark 2.0.1 into an array?</p>

<pre><code>+---+-----+
| id| dist| 
+---+-----+
|1.0|2.0|
|2.0|4.0|
|3.0|6.0|
|4.0|8.0|
+---+-----+
</code></pre>

<p>should return <code>Array(1.0, 2.0, 3.0, 4.0)</code></p>

<p>A</p>

<pre><code>import scala.collection.JavaConverters._ 
df.select("id").collectAsList.asScala.toArray
</code></pre>

<p>fails with</p>

<pre><code>java.lang.RuntimeException: Unsupported array type: [Lorg.apache.spark.sql.Row;
java.lang.RuntimeException: Unsupported array type: [Lorg.apache.spark.sql.Row;
</code></pre>