title: Removing NA observations with dplyr::filter()
body: <p>My data looks like this:</p>
  
  <pre><code>library(tidyverse)
  
  df &lt;- tribble(
      ~a, ~b, ~c,
      1, 2, 3, 
      1, NA, 3, 
      NA, 2, 3
  )
  </code></pre>
  
  <p>I can remove all <code>NA</code> observations with <code>drop_na()</code>:</p>
  
  <pre><code>df %&gt;% drop_na()
  </code></pre>
  
  <p>Or remove all <code>NA</code> observations in a single column (<code>a</code> for example):</p>
  
  <pre><code>df %&gt;% drop_na(a)
  </code></pre>
  
  <p>Why can't I just use a regular <code>!=</code> filter pipe?</p>
  
  <pre><code>df %&gt;% filter(a != NA)
  </code></pre>
  
  <p>Why do we have to use a special function from tidyr to remove NAs?</p>