问题 I am having trouble running commands in new version of R (4.0.1; Platform: x86_64-w64-mingw32/x64 (64-bit)) and RStudio (Version 1.3.959) which worked well in the older version of R. Let's say, I have a table named Check with more than 10,000 rows and more than 100 variables (categorical and numeric). If I try to invoke the droplevels command, I get the below message. Check <- droplevels(Check) Error in .shallow(x, cols = cols, retain.key = TRUE) : can't set ALTREP truelength However, the