title: Summing entries in R based on perfect matches?
body: <p>I have an excel spreadsheet where some researchers caught fish, and then recorded each entry as one catch of fish. Because of this, a lot of information is duplicated. I would like to use some entry matching in R to change the way the spreadsheet looks, but I'm not sure how?</p>
  
  <p>For instance, right now my spreadsheet looks like:</p>
  
  <pre><code>Year  Location  TimeStarted  TimeEnded  Species
  1974  H11       11:00 AM     12:30 PM   Black Rockfish
  1974  H11       11:00 AM     12:30 PM   Black Rockfish
  1974  H11       11:00 AM     12:30 PM   Black Rockfish
  1974  H11       2:00 AM      3:30 AM    Copper Rockfish
  1974  N80       11:00 AM     1:20 PM    Copper Rockfish 
  </code></pre>
  
  <p>And I would like to look like:</p>
  
  <pre><code>Year  Location  TimeStarted  TimeEnded  Black RF  Copper RF
  1974  H11       11:00 AM     12:30 PM   3         0
  1974  H11       2:00 AM      3:30 AM    0         1
  1974  N80       11:00 AM     1:20 PM    0         1
  </code></pre>
  
  <p>So in essence, I need 1.) entries to match perfectly and then if they do, 2.) have R sum the number of species for perfectly matching entries. </p>