[R] extractAIC using surf.ls

[Yan Wong]

On 11 Aug 2006, at 08:17, Prof Brian Ripley wrote:

> Roger, thank you for looking into this.

Yes, and thanks to both of you for the corrections.

> However, the posting guide asked the poster to contact the  
> maintainer. Had
> (s)he done so, I would have pointed out that spatial 7.28-2 (the  
> current
> version for R-devel) has this corrected (in a slightly simpler way).

Thanks. There have been a few times when what I thought was a bug was  
due to a misunderstanding on my part. It seems better to me to check  
on the R-help list that it really is a bug before bothering the  
maintainers.

On that note, I see that Prof. Ripley is the author of the loess  
package. When trying to adjust some of the control parameters for a  
loess fit, I tried the following (wrong) incantation.

loess(dist ~ speed, cars, control = list(statistics = "exact"))

Although it is wrong (should be control = loess.control(statistics =  
"exact")), entering this as a command actually crashes R on the 2  
systems I have tried (OS X, linux, both R-2.3.1), with the error  
below. I'm not sure if you consider this a bug, as the command I  
typed was invalid.

-------------------

  *** caught segfault ***
address (nil), cause 'memory not mapped'

Traceback:
1: .C(R_loess_raw, as.double(y), as.double(x), as.double 
(weights),     as.double(robust), as.integer(D), as.integer(N),  
as.double(span),     as.integer(degree), as.integer(nonparametric),  
as.integer(order.drop.sqr),     as.integer(sum.drop.sqr), as.double 
(span * cell), as.character(surf.stat),     fitted.values = double 
(N), parameter = integer(7), a = integer(max.kd),     xi = double 
(max.kd), vert = double(2 * D), vval = double((D +         1) *  
max.kd), diagonal = double(N), trL = double(1),     delta1 = double 
(1), delta2 = double(1), as.integer(surf.stat ==         "interpolate/ 
exact"))
2: simpleLoess(y, x, w, span, degree, parametric, drop.square,  
normalize,     control$statistics, control$surface, control$cell,  
iterations,     control$trace.hat)
3: loess(dist ~ speed, cars, control = list(statistics = "exact"))

Possible actions:
1: abort (with core dump)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace