| update {stats} | R Documentation |
update will update and (by default) re-fit a model. It does this
by extracting the call stored in the object, updating the call and (by
default) evaluating that call. Sometimes it is useful to call
update with only one argument, for example if the data frame has
been corrected.
update(object, ...) ## Default S3 method: update(object, formula., ..., evaluate = TRUE)
object |
An existing fit from a model function such as lm,
glm and many others. |
formula. |
Changes to the formula – see update.formula for
details. |
... |
Additional arguments to the call, or arguments with
changed values. Use name=NULL to remove the argument name. |
evaluate |
If true evaluate the new call else return the call. |
If evaluate = TRUE the fitted object, otherwise the updated call.
Chambers, J. M. (1992) Linear models. Chapter 4 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.
oldcon <- options(contrasts = c("contr.treatment", "contr.poly"))
## Annette Dobson (1990) "An Introduction to Generalized Linear Models".
## Page 9: Plant Weight Data.
ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
group <- gl(2, 10, 20, labels = c("Ctl", "Trt"))
weight <- c(ctl, trt)
lm.D9 <- lm(weight ~ group)
lm.D9
summary(lm.D90 <- update(lm.D9, . ~ . - 1))
options(contrasts = c("contr.helmert", "contr.poly"))
update(lm.D9)
options(oldcon)