title: How to change value in a Map Datatype
body: <p>I have a dataframe having a column of type <code>MapType&lt;StringType, StringType&gt;</code>.</p>
  <pre class="lang-none prettyprint-override"><code> |-- identity: map (nullable = true)
   |    |-- key: string
   |    |-- value: string (valueContainsNull = true)
  </code></pre>
  <p>Identity column contains a key &quot;update&quot;.</p>
  <pre><code>+-------------+
  identity      |
  +-------+-----+
  [update  -&gt; Y]|
  [update  -&gt; Y]|
  [update  -&gt; Y]|
  [update  -&gt; Y]|
  +-------+-----+
  </code></pre>
  <p>How do I change the value of key &quot;update&quot; from &quot;Y&quot; to &quot;N&quot;?</p>
  <p>I'm using spark version 2.3</p>
  <p>Any help will be appreciated. Thank you!</p>