title: comparing pairs as a separate entry in rows in R
body: <p>I have a column name <code>file</code> which is character variable giving information about left and right wing of insect (<code>L.dw.png</code> and <code>R.dw.png</code>) along with some other attributes.</p>
  <p>I would like to see if any file entry does not exist in pair of left and right wing? Every odd row denotes left wing and every even row denotes right wing.</p>
  <pre><code>wings &lt;- read.table(&quot;https://zenodo.org/record/6950928/files/AT-raw-coordinates.csv&quot;, header = TRUE, sep = &quot;;&quot;)
  </code></pre>
  <p>First six entries are follow</p>
  <pre><code>                          file  sample country  x1  y1  x2  y2  x3  y3  x4  y4
   1 AT-0001-031-003678-L.dw.png AT-0001      AT 219 191 238 190 292 270 287 216
   2 AT-0001-031-003678-R.dw.png AT-0001      AT 213 190 234 189 289 268 281 211
   3 AT-0001-031-003679-L.dw.png AT-0001      AT 218 182 235 181 284 262 286 210
   4 AT-0001-031-003679-R.dw.png AT-0001      AT 214 185 234 183 283 264 285 211
   5 AT-0001-031-003680-L.dw.png AT-0001      AT 207 181 225 178 276 261 273 206
   6 AT-0001-031-003680-R.dw.png AT-0001      AT 203 181 222 180 271 261 267 206
  </code></pre>
  <p>If anyone can help me, i cannot write code script because i tried with few random codes after looking through search engines, which did not satisfy my query.</p>
  <p>If anyone can lead, i shall be greatly thankful.</p>