title: How to count the empty cells in a dataset?
body: <p>I have been trying to determine the number of empty cells in the whole dataset.</p>
  <p>I have used <code>sum(is.na())</code> but, it did not work. It gives the complementary result of <code>sum(complete.cases())</code> gives/shows the complete rows (without any empty cells). I have also tried <code>sum(dat$exampleColumn != &quot;&quot;)</code>. However, I want the number of all empty cells. Does anyone have any suggestions?</p>
  <p>Example data</p>
  <pre><code> Age  ZipCode  Smoke  Activity 
    25    13020    No   3x week
    35    08740    Yes  NULL
    15    NULL          5x week
    42             Yes  
    14    42859    N/A  2x week
  </code></pre>
  <p>There are just three empty cells in this example. I want to reach this value.</p>
  <p><a href="https://i.stack.imgur.com/yzw6Y.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yzw6Y.png" alt="A snapshot of the dataset after uploading to R." /></a></p>
  <p><a href="https://i.stack.imgur.com/EdXCJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EdXCJ.png" alt="Output of dput" /></a></p>