From: Ross Darnell
Maybe a useful addition to the predict functions would be to
return the
values of the predictor variables. It just (unless there are
problems)
requires an extra line. I have inserted an example below.
"predict.glm" <-
function (object, newdata = NULL, type = c("link", "response",
"terms"), se.fit = FALSE,
dispersion = NULL, terms = NULL,
na.action = na.pass, ...)
{
type <- match.arg(type)
na.act <- object$na.action
object$na.action <- NULL
if (!se.fit) {
if (missing(newdata)) {
pred <- switch(type, link = object$linear.predictors,
response = object$fitted, terms =
predict.lm(object,
se.fit =
se.fit, scale
= 1, type = "terms",
terms = terms))
if (!is.null(na.act))
pred <- napredict(na.act, pred)
}
else {
pred <- predict.lm(object, newdata, se.fit, scale = 1,
type = ifelse(type == "link",
"response", type),
terms = terms, na.action = na.action)
switch(type, response = {
pred <- family(object)$linkinv(pred)
}, link = , terms = )
}
}
else {
if (inherits(object, "survreg"))
dispersion <- 1
if (is.null(dispersion) || dispersion == 0)
dispersion <- summary(object, dispersion =
dispersion)$dispersion
residual.scale <- as.vector(sqrt(dispersion))
pred <- predict.lm(object, newdata, se.fit, scale =
residual.scale,
type = ifelse(type == "link",
"response", type),
terms = terms, na.action = na.action)
fit <- pred$fit
se.fit <- pred$se.fit
switch(type, response = {
se.fit <- se.fit * abs(family(object)$mu.eta(fit))
fit <- family(object)$linkinv(fit)
}, link = , terms = )
if (missing(newdata) && !is.null(na.act)) {
fit <- napredict(na.act, fit)
se.fit <- napredict(na.act, se.fit)
}
predictors <- if (missing(newdata)) model.matrix(object)
else newdata
pred <- list(predictors=predictors,
fit = fit, se.fit = se.fit,
residual.scale = residual.scale)
}
pred
#______________________ end of R code
Ross Darnell
--
School of Health and Rehabilitation Sciences
University of Queensland, Brisbane QLD 4072 AUSTRALIA
Email: <r.darnell at uq.edu.au>
Phone: +61 7 3365 6087 Fax: +61 7 3365 4754 Room:822,
Therapies Bldg.
http://www.shrs.uq.edu.au/shrs/school_staff/ross_darnell.html