Filter spark DataFrame on string contains
<p>I am using <a href="http://spark.apache.org/releases/spark-release-1-3-0.html" rel="noreferrer">Spark 1.3.0</a> and <a href="https://github.com/databricks/spark-avro/tree/c5612df9b1a9768689fec91655faa2a7073fd9fc#spark-sql-avro-library" rel="noreferrer">Spark Avro 1.0.0</a>. 
 I am working from <a href="https://github.com/databricks/spark-avro" rel="noreferrer">the example on the repository page</a>.  This following code works well</p>

<pre><code>val df = sqlContext.read.avro("src/test/resources/episodes.avro")
df.filter("doctor &gt; 5").write.avro("/tmp/output")
</code></pre>

<p>But what if I needed to see if the <code>doctor</code> string contains a substring? Since we are writing our expression inside of a string. What do I do to do a "contains"?</p>