[Rd] predict.smooth.spline.fit and Recall() (Was: Re: Return function from function and Recall())

[Henrik Bengtsson]

Hi,

forget about the below details.  It is not related to the fact that
the function is returned from a function.  Sorry about that.  I've
been troubleshooting soo much I've been shoting over the target.  Here
is a much smaller reproducible example:

x <- 1:10
y <- 1:10 + rnorm(length(x))
sp <- smooth.spline(x=x, y=y)
ypred <- predict(sp$fit, x)
# [1]  2.325181  2.756166  ...
ypred2 <- predict(sp$fit, c(0,x))
# Error in Recall(object, xrange) : couldn't find
# function "predict.smooth.spline.fit"

/Henrik


On 4/5/06, Henrik Bengtsson <hb at maths.lth.se> wrote:
> Hi,
>
> yesterday I got very useful feedback on what is the best way to return
> a function from a function.
>
> Now, I run into a problem calling a returned function that down the
> stream uses Recall().  Below is a self-contained example.  I took away
> yesterday's code for returning a minimal environment for the function,
> because that is not related to this problem.
>
> getPredictor <- function(x, y) {
>   sp <- smooth.spline(x=x, y=y, keep.data=FALSE)
>   function(x, ...) predict(sp$fit, x, ...)$y
> }
>
> # Simulate data
> x <- 1:10
> y <- 1:10 + rnorm(length(x))
>
> # Estimate predictor function
> fcn <- getPredictor(x,y)
>
> # No extrapolation => no Recall()
> ypred <- fcn(x)
> print(ypred)
> # Gives:  # [1]  2.325181  2.756166  ...
>
> # With extrapolation => Recall()
> xextrap <- c(0,x)
> ypred <- fcn(xextrap)
> # Gives:  # Error in Recall(object, xrange) : couldn't find
> # function "predict.smooth.spline.fit"
>
> To see what's the function looks like, do
>
> pfcn <- getAnywhere("predict.smooth.spline.fit")$obj[[2]]
> page(pfcn)
>
> A workaround is to set the predict.smooth.spline.fit() in .GlobalEnv, i.e.
>
>  predict.smooth.spline.fit <- pfcn
>
> Does Recall() have a problem because predict.smooth.spline.fit() is
> not exported, or what is going on?  Are there alternatives to the
> above workaround?  I can see how such a workaround can become very
> complicated with complex functions where it is hard to predict what
> functions are called when.
>
> /Henrik
>
> PS, may I suggest to modify page() so that
> 'page(getAnywhere("predict.smooth.spline.fit"))' works? DS.
>


--
Henrik Bengtsson
Mobile: +46 708 909208 (+2h UTC)