I'm an agronomist studying sustainable agriculture. I've had three semesters of graduate level statistics courses that used R, but none covered data manipulation in R, so I'm still learning a lot as I go. I know how to run models and check assumptions, but not how to automate processes or reshape data in certain ways. I did my PhD really fast, so I didn't have time to sort through SO to find fancy tips and tricks that could have helped me along the way.