title: Exclude top and bottom 1% of data in a df in R
body: <p>For a sample dataframe:</p>
  
  <pre><code>set.seed (1000)
  a &lt;- rnorm(1000)
  b &lt;- seq(1, 1000, by=1)
  df &lt;- data.frame(b, a)
  </code></pre>
  
  <p>I want to exclude the top 1% and bottom 1% of my data (column a).</p>
  
  <p>I have read about trim and quantile in R but can't seem to get them to work.</p>
  
  <p>Could someone help explain how I:</p>
  
  <p>a. Set these extremities to NA</p>
  
  <p>b. Delete these extremities off my dataframe</p>