
simplify.formula
rewrites a formula
using shorthand notation.
Currently only the factor crossing operator *
is applied, so that
expanded expression such as a+b+a:b
becomes a*b
.
expand.formula
does the opposite, additionally expanding other
expressions, i.e. all nesting (/
), grouping and ^
.
simplify.formula(x)
expand.formula(x)
a formula
or an object from which it can be extracted (such as
a fitted model object).
# NOT RUN {
simplify.formula(y ~ a + b + a:b + (c + b)^2)
simplify.formula(y ~ a + b + a:b + 0)
expand.formula(~ a * b)
# }
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