My guess would be that your key columns are factors with different levels. You have to be very careful manipulating factors... I recommend using character data until you are ready to do analysis steps that need factors. You may be able to resolve this by importing your data with the as.is=TRUE or stringsAsFactors=FALSE depending what functions you are using (read the help for your input function).
On December 3, 2019 10:02:45 AM PST, Ana Marija <[hidden email]> wrote: