title: How do I clean up R memory without restarting my PC?
body: <p>I am running my code in R (under Windows) which involves a lot of in-memory data. I tried to use <code>rm(list=ls())</code> to clean up memory, but seems the memory is still occupied and I cannot rerun my code. I tried to close the R and restart R again, but it is the same, seems memory is still occupied as when I run the codes it says it can't allocate memory (but it could at the first time). The memory seems only cleaned up after I restart my PC.</p>
  
  <p>Is there any way to clean up the memory so that I can rerun my code without restarting my PC every time?</p>