title: Sort by key in map type column for each row in spark dataframe
body: <p>I have a spark dataframe in the below format:</p>
  <pre><code>Name   LD_Value
  A37    Map(10 -&gt; 0.20,5 -&gt; 0.30,17 -&gt; 0.25)
  A39    Map(11 -&gt; 0.40,6 -&gt; 0.67,24 -&gt; 0.45)
  </code></pre>
  <p>I need to sort based on keys in <code>LD_Value</code> column for each record in descending order.</p>
  <p>Expected output:</p>
  <pre><code>Name   LD_Value
  A37    Map(17 -&gt; 0.25,10 -&gt; 0.20,5 -&gt; 0.30)
  A39    Map(24 -&gt; 0.45,11 -&gt; 0.40,6 -&gt; 0.67)
  </code></pre>
  <p>Is it possible to do sorting on map type column in spark dataframe?</p>
  <p>I looked into spark higher-order functions but no luck.</p>