title: excluding a set of observations in subsetting
body: <p>Suppose I have a data on characteristics of organisms. I want to subset the data on the basis of species. I have under species 50 types of species and I want to subset by excluding one species for example amphibians. What command can help me do that ?
  One way to do it is by writing explicitly the names of all the species explicitly in the subset command as follows</p>
  
  <pre><code>sub &lt;- subset(data, species %in% c("species1,species2,...,species50))  #all species excluding amplhibians.
  </code></pre>
  
  <p>But this will be a very hectic process. How can I use the subset command to get my result ?
  Thanks in advance.</p>