Manipulate model formulas

simplify.formula rewrites a formula into shorthand notation. Currently only the factor crossing operator * is applied, so an 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)

Arguments

x

a formula or an object from which it can be extracted (such as a fitted model object).

Author

Kamil Bartoń

See also

formulastats

delete.response, drop.terms, and reformulate

Examples

simplify.formula(y ~ a + b + a:b + (c + b)^2)
#> y ~ a * b + b * c
#> <environment: 0x55cba8790450>
simplify.formula(y ~ a + b + a:b + 0)
#> y ~ a * b - 1
#> <environment: 0x55cba8790450>

expand.formula(~ a * b)
#> ~a + b + a:b
#> <environment: 0x55cba8790450>