As a footnote, the update.formula function shares one of the flaws I mentioned
in the
earlier post
> test <- y ~ x1 + (x2=='abc') + x3
> update(test, . ~ .-x3)
y ~ x1 + x2 == "abc"
The original formula is valid but the updated one is not.
Terry T.
[[alternative HTML version delete
Martin,
There are a couple of issues with [.terms that have bitten my survival code.
At the
useR conference I promised you a detailed (readable) explanation, and have been
lax in
getting it to you. The error was first pointed out in a bugzilla note from
2016, by the
way. The current sur
