title: How to find multiple underscore in the same string?
body: <p>I have strings with different numbers of underscores. I am trying to select the strings that contain two or more underscores. Any suggestions? </p>
  
  <pre><code>Strings &lt;- c("aa_bb", "aa_bb_cc_dd", "jah_ghtfv_jal")
  </code></pre>
  
  <p>Currently I have:</p>
  
  <pre><code>Match1 &lt;- Strings[grepl("[_].+[_]", Strings) == TRUE,] and
  Match2 &lt;- Strings[grepl("_.*_", Strings) == TRUE,]
  </code></pre>
  
  <p>Both return slightly different counts.  Can anyone come up with a better way to count to return strings that have two or more underscores? </p>
  
  <p>In this case I would like to return "aa_bb_cc_dd, "jah_ghtfv_jal".</p>
  
  <p>Thanks!</p>