title: R split a character string on the second underscore
body: <p>I have character strings with two underscores. Like these</p>
  
  <pre><code>c54254_g4545_i5454
  c434_g4_i455
  c5454_g544_i3
  .
  .
  etc
  </code></pre>
  
  <p>I need to split these strings by the second underscore and I am afraid I have no clue how to do that in R (or any other tool for that sake). I'd be very happy if anyone can sort me out here.
  Thank you
  SM</p>