| update.formula {base} | R Documentation |
Model Updating
Description
update.formula is used to update model formulae.
This typically involves adding or dropping terms,
but updates can be more general.
Usage
update.formula(old, new, ...)
Arguments
old |
a model formula to be updated. |
new |
a formula giving a template which specifies how to update. |
... |
further arguments passed to or from other methods. |
Details
The function works by first identifying the left-hand side
and right-hand side of the old formula.
It then examines the new formula and substitutes
the lhs of the old formula for any occurence
of "." on the left of new, and substitutes
the rhs of the old formula for any occurence
of "." on the right of new.
Value
The updated formula is returned.
See Also
terms, model.matrix.
Examples
update.formula(y ~ x, ~ . + x2) #> y ~ x + x2
update.formula(y ~ x, log(.) ~ . ) #> log(y) ~ x