To ensure a working, shareable and (re)readable code, anyone working with R should follow some good practices.
Clean up the console
When working with RStudio, RStudio stores all the variables in the memory. For consistency, I believe it is safer to clean all those variable before launching any new, unrelated R code.
To do so:
Comment! Comment! Comment!
Good commenting allows the code to be readable by others, and by oneself when some time has passed.