title: How to delete rows between specific column values
body: <p>I have a data.frame with the following structure</p>
  <pre><code>time &lt;- c(0,&quot;start&quot;,200,300,&quot;end&quot;, 500)
  c1 &lt;- c(3.1, &quot;start&quot;, 4.5, 4.1, &quot;end&quot;, 3.5)
  c2 &lt;- c(4.4, &quot;start&quot;, 4.5, 4.1, &quot;end&quot;, 4.8)
  df &lt;- data.frame(time, c1, c2)
  </code></pre>
  <p>I am trying to remove the rows including and between 2 and 5. The final data.frame would then be:</p>
  <pre><code>time  c1   c2
  0     3.1  4.4
  500   3.5  4.8
  </code></pre>
  <p>start and end strings occur throughout the data frame and they are random. I tried shift function however no luck so far.</p>