20200814 You may wish and typically do ignore variables (dataset columns) with constant values as they add no extra information to the analysis.
# Identify variables that have a single value. %>% ds select(all_of(vars)) %>% sapply(function(x) all(x == x[1L])) %>% which() %>% names() %T>% print() -> constants
If you are accumulating a list of variables to ignore then add these constants to that list.
# Add to the variables to be ignored for modelling. %<>% union(constants)ignore
Your donation will support ongoing availability and give you access to the PDF version of this book. Desktop Survival Guides include Data Science, GNU/Linux, and MLHub. Books available on Amazon include Data Mining with Rattle and Essentials of Data Science. Popular open source software includes rattle, wajig, and mlhub. Hosted by Togaware, a pioneer of free and open source software since 1984. Copyright © 1995-2022 Graham.Williams@togaware.com Creative Commons Attribution-ShareAlike 4.0