title: Count the number of missing values in a dataframe Spark
body: <p>I have a <code>dataset</code> with missing values , I would like to get the number of missing values for each columns. Following is what I did , I got the number of non missing values. How can I use it to get the number of missing values?</p>
  <pre class="lang-scala prettyprint-override"><code>df.describe().filter($&quot;summary&quot; === &quot;count&quot;).show
  </code></pre>
  <pre class="lang-none prettyprint-override"><code>+-------+---+---+---+
  |summary|  x|  y|  z|
  +-------+---+---+---+
  |  count|  1|  2|  3|
  +-------+---+---+---+
  </code></pre>
  <p>Any help please to get a <code>dataframe</code> in which we'll find columns and number of missing values for each one.</p>