title: Dataframe too big for even split.data.frame. What else can I try?
body: <p>I'm working with a data.frame that is about 2 million rows, I need to group rows and apply functions to them, and I was using split.data.frame and modify for that.</p>
  <p>Unfortunately the split.data.frame alone breaks the memory limit. I'm working on my company's server, so I can't really install a new r version or add any memory or anything.</p>
  <p>I think I can multi thread the modify part, but first the the splitting needs to be successful.</p>
  <p>What else can I try?</p>