title: How can I assign values in R using row numbers?
body: <p>I have a data frame and I would like to assign a particular value (Say "water") to all elements with row numbers from 10-100 and column 5. I would do the same for another row range of 500-600 in the same column 5.</p>
  
  <p>I can do this separately as I have to do it only 3-4 times. Please let me know how to do it.</p>
  
  <p>Thanks.</p>