R help - Sep 2004 - glm.fit and predict.glm: error ' no terms component'

Hi

when I fit a glm by

	glm.fit(x,y,family = binomial())
	
and then try to use the object for prediction of newdata by:

	predict.glm(object, newdata)

I get the error:

Error in terms.default(object) : no terms component

I know I can use glm() and a formula, but for my case I prefer 
glm.fit(x,y)...


thanks for a hint

christoph

$platform
[1] "i686-pc-linux-gnu"

$arch
[1] "i686"

$os
[1] "linux-gnu"

$system
[1] "i686, linux-gnu"

$status
[1] ""

$major
[1] "1"

$minor
[1] "9.1"

$year
[1] "2004"

$month
[1] "06"

$day
[1] "21"

$language
[1] "R"

On Wed, 29 Sep 2004, Christoph Lehmann wrote:
> Hi
>
> when I fit a glm by
>
> 	glm.fit(x,y,family = binomial())
> 	and then try to use the object for prediction of newdata by:
>
> 	predict.glm(object, newdata)
>
> I get the error:
>
> Error in terms.default(object) : no terms component
>
> I know I can use glm() and a formula, but for my case I prefer 
> glm.fit(x,y)...
Well, you can't use predict.glm that way.  As the function name suggests, 
it is a predict method for objects of class "glm", which in your case
you
do not have.

There are two reasons why it won't work.  For type="terms" the
formula is
needed to identify terms, and for any type of prediction the formula is 
needed to convert the data frame newdata into a model matrix.

You would need to write a function where the new data was a model matrix. 
If you only need point predictions then

predict_glm_fit<-function(glmfit, newmatrix, addintercept=TRUE){
    if (addintercept)
 	newmatrix<-cbind(1,newmatrix)
    eta<-glmfit$coef %*% newmatrix
    family$linkinv(eta)
}

would work.

 	-thomas